Date: Wed, 3 Sep 1997 09:01:57 -0400 (EDT)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: seminar
Welcome back everyone. The MIT combinatorics seminar will resume this
Friday at 4:15pm in 2-338 as usual. The first speaker will be
Christian Lenart on "The Combinatorics of Steenrod Operations on the
Cohomology of Grassmannians." See abstract below.
There are some new aspects to our seminar:
1.This year Jim Propp, Maurice Rojas and I (Sara Billey) will be
organizing the seminar. If you would like to give a talk or know of
anyone who will be in the area that we should invite, please let one
or all of us know: propp(at-sign)math.mit.edu, rojas(at-sign)math.mit.edu,
billey(at-sign)math.mit.edu.
2. We want to invite all of our speakers to contribute an electronic
preprint pertaining to their talk. These preprints will be on the
combinatorics(at-sign)mit web page. One can either give us a pointer to a
homepage or we will put the file on our server. If possible we would
like to have the preprint before the talk is given so people can
familiarize themselves with the work.
3. Our web address has been changed. This should be pretty permanent.
http://www-math.mit.edu/~combin
(We are in the process of updating it for the fall, it will be ready
momentarily.)
4. As usual, if you know anyone who should be added to the list,
please let us know. Likewise, anyone who would like to be removed
from the list can write to us directly. In the next few weeks we will
be installing a email-list maintenance program which will handle
requests for subscriptions and unsubsriptions. We will keep you
posted on this.
Date: Friday Sept. 5, 1997
Speaker: Christian Lenart
Title: The Combinatorics of Steenrod Operations on the Cohomology
of Grassmannians
Abstract:
The study of the action of the Steenrod algebra on the mod $p$
cohomology of spaces has many applications to the topological structure
of those spaces. In this talk we present some combinatorial formulas for
the action of Steenrod operations on the cohomology of Grassmannians,
both in the Borel and the Schubert picture. We consider integral lifts
of Steenrod operations, which lie in a certain Hopf algebra of
differential operators. The latter has been considered recently as a
realization of the Landweber-Novikov algebra in complex cobordism
theory; it also has connections with the action of the Virasoro algebra
on the boson Fock space. Our formulas for Steenrod operations are based
on methods which have not been used before in this area, namely Hammond
operators and the combinatorics of Schur functions. We also discuss
applications of our formulas to the geometry of Grassmannians.
Date: Fri, 5 Sep 1997 10:26:19 -0400 (EDT)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: seminar today
*********Combinatorics Seminar Today at 4:15 in 2-338**********
refreshments served at 3:45
Date: Friday Sept. 5, 1997
Speaker: Christian Lenart
Title: The Combinatorics of Steenrod Operations on the Cohomology
of Grassmannians
Preprint: http://www-math.mit.edu/~combin
Abstract:
The study of the action of the Steenrod algebra on the mod $p$
cohomology of spaces has many applications to the topological structure
of those spaces. In this talk we present some combinatorial formulas for
the action of Steenrod operations on the cohomology of Grassmannians,
both in the Borel and the Schubert picture. We consider integral lifts
of Steenrod operations, which lie in a certain Hopf algebra of
differential operators. The latter has been considered recently as a
realization of the Landweber-Novikov algebra in complex cobordism
theory; it also has connections with the action of the Virasoro algebra
on the boson Fock space. Our formulas for Steenrod operations are based
on methods which have not been used before in this area, namely Hammond
operators and the combinatorics of Schur functions. We also discuss
applications of our formulas to the geometry of Grassmannians.
Upcoming events:
Date: Friday Sept. 12, 1997
Speaker: To be announced
Date: Friday Sept. 19, 1997
Speaker: Itaru Terada
Title: Brauer diagrams, updown tableaux and conjugacy classes of
nilpotent matrices
Date: Wednesday, Sept. 24, 1997
Speaker: Alexander Kirillov
Title: Kazhdan-Lusztig polynomials and canonical basis
Preprint: http://www-math.mit.edu/~combin
Preprints and abstracts will be on http://www-math.mit.edu/~combin as
soon as they are available.
Date: Mon, 8 Sep 1997 15:34:20 -0500
To: combinatorics(at-sign)math.mit.edu, combinatorics(at-sign)euclid.ucsd.edu
From: bergeron(at-sign)mathstat.yorku.ca (Nantel Bergeron)
Subject: FPSAC 98 --- CALL FOR PAPERS
% ********************************************************************** %
% %
% 10-th international Conference on %
% Formal Power Series and Algebraic Combinatorics %
% %
% June 15-19, 1998 %
% Fields Institute, Toronto %
% %
% First announcement -- Call for papers %
% %
% ********************************************************************** %
TOPICS: Algebraic and bijective combinatorics and their relations with
other parts of mathematics, computer science and physics.
CONFERENCE PROGRAM: Invited lectures, contributed presentations,
poster session, software demonstrations.
OFFICIAL LANGUAGES: English and French.
CALL FOR PAPERS AND POSTERS: Authors are invited to submit extended
abstracts of at most twelve pages before November 21, 1997.
Preferred way of submission is by sending ONE postscript file by
email to
bergeron(at-sign)mathstat.yorku.ca.
If an author is not able to send a postscript version of her/his extended
abstract, four copies of the extended abstract should be mailed to
Nantel Bergeron, Program committee of FPSAC '98
Department of Mathematics and Statistics 61
York University
4700 Keele St.
North York, Ontario, Canada, M3J 1P3.
The submitted papers should begin with a summary written in the two
official languages of the conference (translations will be provided
if necessary). Authors should indicate the mode of presentation
which they consider appropriate for their paper : lecture or poster
session. The notifications of acceptance or rejection are scheduled
for the beginning of March 1998.
The authors whose papers will have been accepted for a lecture or a
poster presentation will have the possibility to submit a complete
version of their work to a special issue of the journal ``Discrete
Mathematics," devoted to the conference FPSAC '98. The deadline for
submission to the special issue is September 1, 1998.
SOFTWARE DEMONSTRATIONS: Demonstrations of software relevant to the
topics of the conference are encouraged. People interested in giving
a software demonstration should submit a paper as described above,
including the hardware requirements, before January 15, 1997,
by email to
sottile(at-sign)math.toronto.edu.
PROGRAM COMMITTEE:
I. Goulden, Chairman (U. of Waterloo), N. Bergeron (York U.),
S. Billey (USA), F. Brenti (Italy), R. Cori (France), S. Dulucq (France)
K. Eriksson (Sweeden), O. Foda (Australia), S. Fomin (USA), I. Gessel (USA),
C. Greene (USA), A. Hamel (England), D. Kim (Korea),
C. Krattenthaler (Austria), D. Krob (France), M. Noy (Spain), V. Reiner (USA),
C. Reutenauer (UQAM), F. Sottile (U. Toronto), T. Visentin (U. Winnipeg).
M. Wachs (USA), H. Yamada (Japan), G. Ziegler (Germany).
PARTICIPANT SUPPORT: Limited funds are available for partial support of
participants. Requests should contain a letter of recommendation and
include the estimated transportation and living expenses as well as the
amount of support available from other sources. All requests should be sent
in duplicate by January 15, 1998 to the following address :
Walter Whiteley, Organizing committee of FPSAC '98
Department of Mathematics and Statistics 61
York University
4700 Keele St.
North York, Ontario, Canada, M3J 1P3.
whiteley(at-sign)mathstat.yorku.ca
LOCATION: The conference will take place at the Fields Institute in
Toronto, Canada. The first talk is scheduled on June 15, 1998 at 9:00 a.m.
FURTHER INFORMATION: A WWW site
http://www.math.yorku.ca/bergeron
has been set up for the conference which will always contain the latest state
of affairs. For any further question, just write to
bergeron(at-sign)mathstat.yorku.ca.
ORGANIZING COMMITTEE
N. Bergeron, Chairman (York U.), M. Delest (U. de Bordeaux),
F. Sottile (U. Toronto), W. Whiteley (York U.).
Nantel Bergeron bergeron(at-sign)mathstat.yorku.ca
Associate Prof. Mathematics nantel(at-sign)math.harvard.edu
York University nantel(at-sign)lacim.uqam.ca
http://www.math.yorku.ca/bergeron
Date: Wed, 10 Sep 1997 18:37:45 -0400 (EDT)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Combinatorics seminar update:
Date: Friday, Sept. 12, 1997
Speaker: Jozsef Losonczy, CUNY-Graduate Center
Title: Arithmetical matchings
Abstract:
Our goal is to generalize the following known matching property of
lattices as far as possible to an arbitrary abelian group. Let G be a
lattice (discrete additive subgroup of R^n). Suppose we
are given m lattice points and m direction vectors from G. Then it is
possible to pair the lattice points with the direction vectors in
one-to-one fashion so that the sum within each pair is not one of the
given lattice points; moreover, this can be done in such a way that
the pairing is uniquely determined by the lattice points, direction
vectors and multiset of sums.
After discussing two approaches to proving the lattice formulation (one
due jointly to Alon, Fan, Kleitman and Losonczy), we describe how the
Dyson e-transform, the Cauchy-Davenport inequality and other tools from
additive number theory can be used to prove the existence of admissible
pairings (matchings) in a more general setting.
Preprint: http://www-math.mit.edu/~combin
Date: Fri, 12 Sep 1997 11:22:22 -0400 (EDT)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: seminar today
*********Combinatorics Seminar Today at 4:15 in 2-338**********
refreshments served at 3:45
Date: Friday, Sept. 12, 1997
Speaker: Jozsef Losonczy, CUNY-Graduate Center
Title: Arithmetical matchings
Preprint: http://www-math.mit.edu/~combin
Abstract:
Our goal is to generalize the following known matching property of
lattices as far as possible to an arbitrary abelian group. Let G be a
lattice (discrete additive subgroup of $R^n$). Suppose we
are given m lattice points and m direction vectors from G. Then it is
possible to pair the lattice points with the direction vectors in
one-to-one fashion so that the sum within each pair is not one of the
given lattice points; moreover, this can be done in such a way that
the pairing is uniquely determined by the lattice points, direction
vectors and multiset of sums.
After discussing two approaches to proving the lattice formulation (one
due jointly to Alon, Fan, Kleitman and Losonczy), we describe how the
Dyson e-transform, the Cauchy-Davenport inequality and other tools from
additive number theory can be used to prove the existence of admissible
pairings (matchings) in a more general setting.
Upcoming events:
Date: Wednesday, Sept. 17, 1997
Speaker: Igor Pak (MIT/Yale)
Title: Ribbon Tile Invariants
Date: Friday, Sept. 19, 1997
Speaker: Itaru Terada
Title: Brauer diagrams, updown tableaux and conjugacy classes of
nilpotent matrices
Date: Wednesday, Sept. 24, 1997
Speaker: Alexander Kirillov
Title: Kazhdan-Lusztig polynomials and canonical basis
Date: Friday, Sept. 26, 1997
Speaker: Alex Postnikov
Title: Hidden symmetries of Gromov-Witten invariants
See http://www-math.mit.edu/~combin for more information.
Date: Tue, 16 Sep 1997 13:29:50 -0400 (EDT)
From: Jim Propp <propp(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: M.I.T. combinatorics seminar: upcoming talks
UPCOMING MIT COMBINATORICS SEMINARS:
Ribbon Tile Invariants
Igor Pak (MIT)
Room 2-338
----> 16:15, Wednesday, September 17, 1997 <---- * tomorow! *
Consider the problem of tiling a region on a square grid by a given set of
tiles. You can use the same tile many times, but only translations are allowed
(no rotations or reflections). There are two types of questions you can ask:
(1) Are there any tilings of a given region?
(2) If there are, what do these tilings look like?
While most people were traditionally concerned with the first question, in
our work we are dealing with the second question. Namely, in a case of ribbon
tiles (also called rim hooks in a different context) we were able to find all
the affine linear relations for the number of times each tile can occur in a
tiling. This generalizes the Conway-Lagarias Theorem and explains certain
results regarding characters of the symmetric groups.
The crucial part of the proof is the Stanton-White bijection and its
generalization. We also give some applications to tileability (the first
question).
Brauer Diagrams, Updown Tableaux and Conjugacy Classes of Nilpotent Matrices
Professor Itaru Terada (University of Tokyo)
Room 2-338
16:15, Friday, September 19, 1997
We give a geometric interpretation of S. Sundaram's correspondence, or the
one modified by T. Roby, between the Brauer diagrams on 2n points and the
updown tableaux of length 2n which both start and end at the empty shape.
Our interpretation is an analogue of R. Steinberg's result on the original
Robinson-Schensted correspondence, which describes the relative position of
a generic pair of complete flags fixed by a unipotent transformation and
having a prescribed pair of sequences of types under it.
Our result uses pairs of a nondegenerate symplectic form and a complete flag
instead of pairs of complete flags, and has been inspired by works by Oshima
and Matsuki on orbit decompositions of symmetric spaces.
Kazhdan-Lusztig Polynomials and Canonical Bases
Alexander Kirillov (MIT)
Room 2-338
16:15, Wednesday, September 24, 1997
We show that the Kazhdan-Lusztig polynomials (and, more generally, parabolic
KL polynomials) for the group S_n coincide with the coefficients of the
canonical basis in the nth tensor power of the fundamental representation of
the quantum group U_q SL_k. We also use known results about canonical bases
for U_q SL_2 to get a new, simple proof of the recurrent formulas for KL
polynomials for maximal parabolic subgroups (geometrically, this case
corresponds to Grassmanians), due to Lascoux-Schutzenberger and Zelevinsky.
This is joint work with I. Frenkel and M. Khovanov.
Hidden Symmetries of Gromov-Witten Invariants
Alex Postnikov (MIT)
Room 2-338
16:15, Friday, September 26, 1997
Gromov-Witten invariants of flag manifolds generalize the intersection numbers
of Schubert varieties (aka Littlewood-Richardson coefficients). Their study
and explicit calculation is an important problem in quantum Schubert calculus.
The aim of the talk is to present certain symmetries of these invariants under
the action of cyclic groups. This allows one to calculate 1/n of all these
invariants.
Date: Fri, 19 Sep 1997 11:44:04 -0400 (EDT)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: seminar today
*********Combinatorics Seminar Today at 4:15 in 2-338**********
refreshments served at 3:45
Date: Friday, Sept. 19, 1997
Speaker: Prof. Itaru Terada (University of Tokyo)
Title: Brauer diagrams, updown tableaux and conjugacy classes of
nilpotent matrices
We give a geometric interpretation of S. Sundaram's correspondence,
or the one modified by T. Roby, between the Brauer diagrams on 2n
points and the updown tableaux of length 2n which both start and
end at the empty shape.
Our interpretation is an analogue of R. Steinberg's result on the
original Robinson-Schensted correspondence, which describes the
relative position of a generic pair of complete flags fixed by a
unipotent transformation and having a prescribed pair of sequences of
types under it.
Our result uses pairs of a nondegenerate symplectic form and a
complete flag instead of pairs of complete flags, and has been
inspired by works by Oshima and Matsuki on orbit decompositions of
symmetric spaces.
Date: Wednesday, Sept. 24, 1997
Speaker: Alexander Kirillov
Title: Kazhdan-Lusztig polynomials and canonical basis
Date: Friday, Sept. 26, 1997
Speaker: Alex Postnikov
Title: Hidden symmetries of Gromov-Witten invariants
See http://www-math.mit.edu/~combin for more information.
Date: Wed, 24 Sep 1997 13:59:17 -0400 (EDT)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: seminar today
*********Combinatorics Seminar Today at 4:15 in 2-338**********
refreshments served at 3:45
Date: Wednesday, Sept. 24, 1997
Speaker: Alexander Kirillov
Title: Kazhdan-Lusztig polynomials and canonical basis
Abstract:
We show that the Kazhdan-Lusztig polynomials
(and, more generally, parabolic KL polynomials) for the group
S_n coincide with the coefficients of the canonical basis in the
nth tensor power of the fundamental representation of the
quantum group <it>U_q SL_k</it>. We also use known results about canonical
bases for <it>U_q SL_2</it> to get a new, simple proof of the recurrent
formulas for KL polynomials for maximal parabolic subgroups
(geometrically, this case corresponds to Grassmanians), due to
Lascoux-Schutzenberger and Zelevinsky. This is joint work with
I. Frenkel and M. Khovanov.
Date: Friday, Sept. 26, 1997
Speaker: Alex Postnikov
Title: Hidden symmetries of Gromov-Witten invariants
Date: Wednesday, October 1, 1997
**Holiday--No seminar**
Date: Friday, October 3, 1997
Speaker: Peter Magyar (Northeastern University)
Title:
Date: Wednesday, October 8, 1997
Speaker: Irena Peeva(MIT)
Title: Resolving a monomial ideal by a simplicial complex
Date: Friday, October 10, 1997
**Holiday--No seminar**
See http://www-math.mit.edu/~combin for more information.
Date: Fri, 26 Sep 1997 13:11:55 -0400 (EDT)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: seminar today
*********Combinatorics Seminar Today at 4:15 in 2-338**********
refreshments served at 3:45
Date: Friday, Sept. 26, 1997
Speaker: Alex Postnikov
Title: Hidden symmetries of Gromov-Witten invariants
Abstract:
Gromov-Witten invariants of flag manifolds generalize the intersection
numbers of Schubert varieties (aka Littlewood-Richardson
coefficients). Their study and explicit calculation is an important
problem in quantum Schubert calculus. The aim of the talk is to
present certain symmetries of these invariants under the action of
cyclic groups. This allows one to calculate 1/n of all these
invariants.
Date: Wednesday, October 1, 1997
**Holiday--No seminar**
Date: Friday, October 3, 1997
Speaker: Peter Magyar (Northeastern University)
Title:
Date: Wednesday, October 8, 1997
Speaker: Irena Peeva(MIT)
Title: Resolving a monomial ideal by a simplicial complex
Date: Friday, October 10, 1997
**Holiday--No seminar**
See http://www-math.mit.edu/~combin for more information.
Date: Wed, 1 Oct 1997 16:01:57 -0400 (EDT)
From: Jim Propp <propp(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: New URL
The URL for the archives of the MIT Combinatorics Seminar is now
http://www-math.mit.edu/~combin/archive/
Please change your pointers accordingly.
Jim Propp
Date: Fri, 3 Oct 1997 10:18:13 -0400 (EDT)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: seminar today
*********Combinatorics Seminar Today at 4:15 in 2-338**********
refreshments served at 3:45
For each partition with parts less than n, there is a variety of
partial flags of subspaces in an n-dimensional vector space. We use
V. Kac's method of quiver representations to answer the question: For
which tuples of partitions does the group $GL(n)$ act on the
corresponding product of partial flag varieties with finitely many
orbits? (For a single flag variety, these orbits are Schubert cells.)
We describe the poset (Bruhat order) given by closures of these
orbits. Joint work with J. Weyman and A. Zelevinsky.
Date: Wednesday, October 8, 1997
Speaker: Irena Peeva(MIT)
Title: Resolving a monomial ideal by a simplicial complex
Date: Friday, October 10, 1997
**Holiday--No seminar**
Date: Friday, October 17, 1997
Speaker: Bernd Sturmfels (RIMS Kyoto and UC Berkeley)
Title: Groebner deformations of A-hypergeometric equations
Date: Wednesday, October 22, 1997
Speaker: Mark Haiman (UCSD)
Title: To Be Announced
See http://www-math.mit.edu/~combin for more information.
Date: Fri, 3 Oct 1997 11:37:01 -0400 (EDT)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: seminar today (again)
Woops, it was pointed out that I left out some important information
in my last message.
*********Combinatorics Seminar Today at 4:15 in 2-338**********
refreshments served at 3:45
Date: Friday, October 3, 1997
Speaker: Peter Magyar (Northeastern University)
Title: Bruhat order on quiver varieties
For each partition with parts less than n, there is a variety of
partial flags of subspaces in an n-dimensional vector space. We use
V. Kac's method of quiver representations to answer the question: For
which tuples of partitions does the group $GL(n)$ act on the
corresponding product of partial flag varieties with finitely many
orbits? (For a single flag variety, these orbits are Schubert cells.)
We describe the poset (Bruhat order) given by closures of these
orbits. Joint work with J. Weyman and A. Zelevinsky.
Date: Wednesday, October 8, 1997
Speaker: Irena Peeva(MIT)
Title: Resolving a monomial ideal by a simplicial complex
Date: Friday, October 10, 1997
**Holiday--No seminar**
Date: Friday, October 17, 1997
Speaker: Bernd Sturmfels (RIMS Kyoto and UC Berkeley)
Title: Groebner deformations of A-hypergeometric equations
Date: Wednesday, October 22, 1997
Speaker: Mark Haiman (UCSD)
Title: To Be Announced
See http://www-math.mit.edu/~combin for more information.
Date: Wed, 8 Oct 1997 13:50:38 -0400 (EDT)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: seminar today
*********Combinatorics Seminar Today at 4:15 in 2-338**********
refreshments served at 3:45
Date: Wednesday, October 8, 1997
Speaker: Irena Peeva(MIT)
Title: Resolving a monomial ideal by a simplicial complex
Preprint: http://www-math.mit.edu/~combin/preprints/Peeva97.ps
This is a joint work with Dave Bayer (Columbia Univ) and
Bernd Sturmfels (Univ of California, Berkeley).
Let M be a monomial ideal in the polynomial ring
S=k[x_1,... ,x_n] over a field k. We are interested
in the problem, first posed by Kaplansky in the early 1960's,
of finding a minimal free resolution of S/M over S.
The difficulty of this problem is reflected in the fact that
the homology of arbitrary simplicial complexes can be encoded
via the Stanley-Reisner correspondence into the multigraded
Betti numbers of S/M. In particular, the minimal
free resolution may depend on the characteristic of k.
We introduce an approach of resolving by encoding the whole
resolution (including the differential maps) into a single
simplicial complex. We prove that generically such a resolution
is minimal and comes from the boundary of a polytope. We
resolve (non-minimally) an arbitrary monomial ideal by
deforming it to a generic one.
Background: I will assume familiarity with Section 11 in
Chapter I in the book "Combinatorics and commutative algebra"
by R. Stanley.
Upcoming events:
Date: Friday, October 10, 1997
**Holiday--No seminar**
Date: Wednesday, October 15, 1997
No Seminar
Date: Friday, October 17, 1997
Speaker: Bernd Sturmfels (RIMS Kyoto and UC Berkeley)
Title: Groebner deformations of A-hypergeometric equations
Preprint: http://www-math.mit.edu/~combin/preprints/Sturmfels97.ps
Date: Wednesday, October 22, 1997
Speaker: Mark Haiman (UCSD)
Title: Macdonald polynomials, Hilbert Schemes and the $n$-Factorial Conjecture
Date: Friday, October 24, 1997
Speaker: Venkat Lakshmibai (Northeastern University)
Title: Tangent Spaces to Schubert Varieties
Date: Wednesday, October 29, 1997
Speaker: Open Mike Day
Title: (hosted by Jim Propp)
Date: Friday, October 31, 1997
Speaker: Robin PEMANTLE
Title: Linear recursions in two variables
Date: Thu, 9 Oct 1997 14:01:20 -0400 (EDT)
From: Richard Stanley <rstan(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: [WEYMAN(at-sign)neu.edu: Buchsbaum Conference Schedule and Directions.]
------- Start of forwarded message -------
Dear Combinatorialists,
Here is some information on a meeting to be held soon at Northeastern
University that might be of interest. It is a conference in honor of
David Buschsbaum.
Richard
___________________________________________________________________
Saturday, 18 October, 105 New Classroom Building
9:00-9:50 J. Green, Discrete series characters for GL(n,q),
coffee
10:30-11:20 W. Fulton, Chern class formulas for degeneracy loci,
lunch
1:30-2:20 M. Ringel, Quasihereditary algebras and their $\Delta$-good modules
tea
3:00-3:50 G-C. Rota, Invariants under translation,
4:20-4:40 P. Freyd, TBA,
4:50-5:10 M. Klucznik, Letterplace techniques in representation theory of
general linear group,
5:30-5:50 H-B. Foxby, Auslander-Buchsbaum Equalities and Restricted
Tor-dimension,
dinner at 7, at the Thai restaurant Sawasdee, 320 Washington St.,
Brookline, cost at approximately $25. Graduate students will
be subsidized.
Sunday, 19 October, 105 New Classroom Building
9;00-9:50 A. Lascoux, Classes of determinantal varieties and Postulation,
coffee
10:30-11:20V. Lakshmibai,Schubert varieties - their relationship
to toric varities,ladder determinantal varieties and quivers,
11:50-12:40 M. Haiman, Macdonald polynomials and Hilbert schemes,
lunch
2:30-3:20 C. DeConcini, On the cohomology of Artin groups,
tea
3:50-4:40 B. Sturmfels, Combinatorial Resolutions.
5:00 poster session.
Monday 20 October, 320, Curry Student Center
9:00-9:50 K. Akin, The resolutions of determinantal varieties and superalgebra
coffee
10:30-11:20 H. Srinivasan, A Question on Determination
lunch
1:30-2:20 R. Stanley, Characteristic polynomials of hyperplane arrangements,
tea
3:00-3:50 A. Zelevinsky, Multiple flag varieties of finite type,
4:20-4:40 D. Leites, Quivers and Lie superalgebras,
4:50-5:10 M. Hashimoto, Buchsbaum-Rim type resolutions of determinantal
ideals,
5:20-5:40 S. Kleiman, Conormal geometry of maximal minors.
Directions:
To get to the New Classroom Building just follow the Forsyth Street
from the crossing of Huntington Av. with Forsyth Street
( one block from Museum of Fine Arts )
into the campus. After passing the crossing with Greenleaf Street,
this is the second building on the right. The room 105 is on the first
floor, on the right side of the building.
The parking garage is located in Columbus Av., you should turn right from
Massachusetts Av. into Columbus Av. ( if you are coming from Symphony
Hall ) and the parking garage is located 2 blocks away, on the right side.
The best access by Green line is to walk from the Auditorium Station. You
walk along Massachsetts Avenue, towards Symphony Hall and turn right
to Huntington Avenue. Then walk two blocks to come to the crossing with
Forsyth Street.
In the case of rain, another possibility ( longer but involving no walking )
is to go to Arlington Station, then taking part E of the green line outbound
which has a stop on the corner of Huntington Av. and Forsyth St.
If you come by orange line, come to the Ruggles Station. As you leave the
station towards Northeastern campus, you see the New Classroom Building
in front of you.
If you arrive on Friday, you are welcome to come to the Department on Friday
late afternoon. The organizers will be there, we plan to go to an informal
dinner to a nearby restaurant with all people that arrive, at about 7PM.
The Department is located in Lake Hall ( the building at the corner of
Forsyth Street and Greenleaf Street ). Turn to Greenleaf Street to find
the entrance "Lake Hall" and go to the 4-th floor. The offices of Alex M.
and Jerzy W. are located there.
Please let me know if there are any problems. Best regards.
Jerzy Weyman.
------- End of forwarded message -------
Date: Wed, 15 Oct 1997 12:59:26 -0400 (EDT)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: no seminar today
There is no combinatorics seminar today. The seminar schedule is now
booked every Wednesday and Friday for the entire semester (except for
today and the day before Thanksgiving). Below is the schedule for the
next few weeks of talks. Please note that several preprints are
available on our web page. See you Friday.
Date: Friday, October 17, 1997
Speaker: Bernd Sturmfels (RIMS Kyoto and UC Berkeley)
Title: Groebner deformations of A-hypergeometric equations
**Preprint Available*** http://www-math.mit.edu/~combin/
Date: Wednesday, October 22, 1997
Speaker: Mark Haiman (UCSD)
Title: Macdonald polynomials, Hilbert Schemes and the $n$-Factorial Conjecture
Date: Friday, October 24, 1997
Speaker: Venkat Lakshmibai (Northeastern University)
Title: Tangent Spaces to Schubert Varieties
Date: Wednesday, October 29, 1997
Speaker: Open Mike Day
Title: (hosted by Jim Propp)
Date: Friday, October 31, 1997
Speaker: Robin PEMANTLE
Title: Linear recursions in two variables
Date: Wednesday, November 5, 1997
Speaker: James Haglund
Title: $q$-Rook polynomials and matrices over finite fields
**Preprint Available*** http://www-math.mit.edu/~combin/
Date: Friday, November 7, 1997
Speaker: Rod Canfield
Title: Maximum Sized Antichains in the Partition Lattice
**Preprint Available*** http://www-math.mit.edu/~combin/
Date: Fri, 17 Oct 1997 11:55:54 -0400 (EDT)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: seminar today
*********Combinatorics Seminar Today at 4:15 in 2-338**********
refreshments served at 3:45
Date: Friday, October 17, 1997
Speaker: Bernd Sturmfels (RIMS Kyoto and UC Berkeley)
Title: Groebner deformations of A-hypergeometric equations
**Preprint Available*** http://www-math.mit.edu/~combin/
We apply Groebner basis theory to study the A-hypergeometric system
of differential equations which was defined by Gel'fand, Kapranov and
Zelevinsky for any lattice configuration A. This system is holonomic;
its rank equals vol(A) if the toric ideal of A is Cohen-Macaulay or
if the parameters are generic, but its rank may exceed vol(A) otherwise.
To bound the rank and to construct series solutions for all parameters values,
we introduce the initial ideal of the A-hypergeometric system with respect
to a suitable term order. The initial ideal contains the ideal of indicial
polynomials (in the sense of Frobenius), and they are equal generically.
Our goal is to determine all solutions of the indicial ideal and to identify
which ones arise from A-hypergeometric series. In this talk we present results
for the case when the underlying triangulation of A is unimodular. This is
joint work in progress with Nobuki Takayama (Kobe) and Mutsumi Saito (Sapporo).
Date: Wednesday, October 22, 1997
Speaker: Mark Haiman (UCSD)
Title: Macdonald polynomials, Hilbert Schemes and the $n$-Factorial Conjecture
Date: Friday, October 24, 1997
Speaker: Venkat Lakshmibai (Northeastern University)
Title: Tangent Spaces to Schubert Varieties
Date: Wednesday, October 29, 1997
Speaker: Open Mike Day
Title: (hosted by Jim Propp)
Date: Friday, October 31, 1997
Speaker: Robin PEMANTLE
Title: Linear recursions in two variables
Date: Wednesday, November 5, 1997
Speaker: James Haglund
Title: $q$-Rook polynomials and matrices over finite fields
**Preprint Available*** http://www-math.mit.edu/~combin/
Date: Friday, November 7, 1997
Speaker: Rod Canfield
Title: Maximum Sized Antichains in the Partition Lattice
**Preprint Available*** http://www-math.mit.edu/~combin/
Date: Fri, 17 Oct 1997 15:23:06 -0400 (EDT)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: changes
It has just come to my attention that several people are interested in
attending both the combinatorics seminar and the algebraic geometry
seminar today. Therefore, we have decided to combine the two seminars
and have each person speak for 45 mins. In order to accommodate both
audiences we will start at 4:00 and we have gotten a bigger classroom
*4-163*.
4:00 Keith Pardue (Queen's University)
What can be preserved under deformation?
4:45 Bernd Sturmfels (RIMS Kyoto and UC Berkeley)
Groebner deformations of A-hypergeometric equations
Below is Pardue's abstract:
Hartshorne proved in his thesis that subschemes of projective space
may be deformed to one another if and only if they have the same
Hilbert polynomial. These deformations may be realized as sequences
of deformations over projective lines. If the subschemes have more
properties in common, then can these properties be preserved while
performing the deformations? I show that certain properties, including
the Hilbert functions and the depths of the subschemes, can be
preserved while deforming one to the other, with the deformations
realized as sequences of deformations over affine lines. In
particular, an arithmetically Cohen-Macaulay subscheme of projective
space may be deformed to any other arithmetically Cohen-Macaulay
subscheme of projective space having the same Hilbert function, with
all of the fibers of the deformations being arithmetically
Cohen-Macaulay with the same Hilbert function. I prove similar
theorems for deformations of finitely generated graded modules over a
polynomial ring.
Date: Sun, 19 Oct 1997 14:28:40 -0400 (EDT)
From: Jim Propp <propp(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: Oct. 29: Open Mike
This is a reminder that the Wednesday, October 29 meeting of the MIT
Combintorics Seminar will be an "open mike" session. To make things
run as smoothly as possible, all those who are interested in making a
short presentation at this session should contact me (propp(at-sign)math.mit.edu)
ahead of time.
Jim Propp
Date: Tue, 21 Oct 1997 15:56:54 -0400 (EDT)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: Special seminar
Two things:
1) Mark Haiman will be speaking tomorrow in the combinatorics seminar.
Anyone who wants go to lunch with him can meet at my office at 12:30.
We will go to the faculty lunch on the second floor of Walker.
2) We will have a special seminar on Thursday at 3:00pm in 2-338 that
should be interesting to combinatorialists:
Speaker: Alain Lascoux
Title: Bruhat order on finite Coxeter groups
Abstract: Bruhat order on Coxeter groups is usually defined by
considering subwords of reduced decompositions. With
M.P. Schutzenberger, I obtain a decomposition of the order by
embedding the group into a lattice. In the case of the symmetric
group, the lattice is distributive, and its vertices can be
identified with the alternating sign matrices.
Date: Tue, 21 Oct 1997 20:05:59 -0400 (EDT)
From: G-C Rota <rota(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: something to share with you.
I am happy to inform you that our former student William Y.C.Chen has
just been awarded a big international prize. Here is the message I just
got:
Dear Gian-Carlo,
Good news -- I just learned that I got the Javed Jusain Prize. Thank you
so much for your support and for your strategy.
Things are going very well here. I will report to you in more detail later.
I am in a rush (the building is being closed [at a regular hour]), and will
write to you later.
Thanks again.
Bill
Date: Wed, 22 Oct 1997 13:34:51 -0400 (EDT)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: seminar today
*********Combinatorics Seminar Today at 4:15 in 2-338**********
refreshments served at 3:45
Date: Wednesday, October 22, 1997
Speaker: Mark Haiman (UCSD)
Title: Macdonald polynomials, Hilbert Schemes and the $n$-Factorial Conjecture
Abstract: I'll give an introduction to certain easily defined spaces
which have remarkable conjectured combinatorial interpretations. The
conjectures have turned out to be surprisingly difficult, and it has
gradually become clear that there is some fundamental algebraic
geometry behind them, involving the Hilbert scheme of points in the
plane, which I'll briefly explain.
Upcoming Events:
Date: Friday, October 24, 1997
Speaker: Venkat Lakshmibai (Northeastern University)
Title: Tangent Spaces to Schubert Varieties
Date: Wednesday, October 29, 1997
Speaker: Open Mike Day
Title: (hosted by Jim Propp)
Date: Friday, October 31, 1997
Speaker: Robin PEMANTLE
Title: Linear recursions in two variables
Date: Fri, 24 Oct 1997 10:03:09 -0400 (EDT)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu, combinatorics(at-sign)euclid.ucsd.edu
Subject: Conference Announcement (text and latex)
ICM 1998 Satellite Conference
``Representations of finite groups and combinatorics''
August 10-14, 1998
Magdeburg, Germany
First Announcement
This is a satellite conference to the ICM 1998 taking place at the
Otto-von-Guericke University of Magdeburg, located about 150 km
west of Berlin; it focuses on those areas of representation theory
of finite groups which have strong connections with combinatorics,
the related combinatorics of partitions and tableaux, the theory of
symmetric functions, and related areas.
The program will be scheduled from Monday morning to Friday evening,
with arrival on Sunday, August 9, and departure on Saturday, August 15.
Organizers:
C. Bessenrodt (Magdeburg),
A. O. Morris (Aberystwyth),
J. B. Olsson (Copenhagen).
At present, the following principal speakers have accepted the invitation:
Karin Erdmann (Oxford, Great Britain)
Phil Hanlon (Ann Arbor, USA)
Gordon James (London, Great Britain)
Alexander Kleshchev (Eugene, USA)
Peter Littelmann (Strasbourg, France)
Ian Macdonald (London, Great Britain)
Gunter Malle (Heidelberg, Germany)
Bhama Srinivasan (Chicago, USA)
Richard Stanley (Boston, USA)
In addition to the one hour lectures by the principal speakers
it is planned to have further talks by the participants on the
following topics:
Representation theory of symmetric and related groups
Representations of finite groups of Lie type
Representations of Hecke algebras and q-Schur algebras
Combinatorics of partitions and tableaux
New combinatorial concepts for studying representations
Symmetric functions
Relations to other areas, such as invariant theory and physics
Accommodation:
There are a limited number of guest rooms on campus, and hotels
within walking distance.
Registration:
Please preregister, preferably by email, until the end of 1997;
due to space restrictions the number of participants will be limited.
Early 1998 we will send out further information such as a hotel list,
registration form etc.
Conference fee: 80 DM
We plan to create a website for the conference with
up-to-date information; please check the homepage for the ICM 98
http://elib.zib.de/ICM98
for the link to this website.
Contact Address:
ICM Satellite Conference
Institut f"ur Algebra und Geometrie
Fakult"at f"ur Mathematik
Otto-von-Guericke-Universit"at Magdeburg
D-39016 Magdeburg, Germany
email: icmsat98(at-sign)uni-magdeburg.de
-------------- latex-file --------------------------------------
\documentstyle[12pt]{article}
\setlength{\oddsidemargin}{0cm}
\setlength{\headheight}{0pt}
\setlength{\headsep}{0pt}
\setlength{\textheight}{23cm}
\setlength{\textwidth}{16cm}
\parindent=0cm
\begin{document}
\begin{center}
{{\large \sc ICM 1998 Satellite Conference}\\[1ex]
\Large \bf ``Representations of finite groups and combinatorics''\\[1ex]
\large \bf August 10-14, 1998 \\
Magdeburg, Germany\\[1ex]
First Announcement}
\end{center}
\vspace{2ex}
This is a satellite conference taking place at the
Otto-von-Guericke University of Magdeburg,
located about 150 km west of Berlin;
it focuses on those
areas of representation theory of finite groups which
have strong connections with combinatorics,
the related combinatorics of partitions and tableaux,
the theory of symmetric functions,
and related areas.
\vspace{2ex}
The program will be scheduled from Monday morning to Friday evening,
with arrival on Sunday, August 9, and departure on Saturday, August 15.
\vspace{2ex}
{\bf Organizers}:\\
C.\ Bessenrodt (Magdeburg),
A.~O.\ Morris (Aberystwyth),
J.~B.\ Olsson (Copenhagen).\\
\vspace{2ex}
At present, the following {\bf principal speakers} have
accepted the invitation:
\begin{center}
\parbox[t]{10cm}{
Karin Erdmann (Oxford, Great Britain)\\
Phil Hanlon (Ann Arbor, USA)\\
Gordon James (London, Great Britain)\\
Alexander Kleshchev (Eugene, USA)\\
Peter Littelmann (Strasbourg, France)\\
Ian Macdonald (London, Great Britain)\\
Gunter Malle (Heidelberg, Germany)\\
Bhama Srinivasan (Chicago, USA)\\
Richard Stanley (Boston, USA)}
\end{center}
In addition to the one hour lectures by the principal speakers
it is planned to
have further talks by the participants on
the following topics:
\begin{center}
\parbox[t]{13cm}{
Representation theory of symmetric and related groups\\
Representations of finite groups of Lie type\\
Representations of Hecke algebras and $q$-Schur algebras \\
Combinatorics of partitions and tableaux \\
New combinatorial concepts for studying representations \\
Symmetric functions \\
Relations to other areas, such as invariant theory and physics}
\end{center}
\vspace{1ex}
{\bf Accommodation:} There are a limited number of guest rooms on campus,
and hotels within walking distance. \\
{\bf Registration:}
Please preregister, preferably by email, until the end of 1997;
due to space restrictions the number of participants will be limited.
Early 1998 we will send out further information such as a hotel list,
registration form etc. \\
{\bf Conference fee:} 80 DM \\
We plan to create a website for the conference with
up-to-date information; please check the homepage for the ICM 98
\centerline{\bf http://elib.zib.de/ICM98}
for the link to this website. \\
{\bf Contact Address:} \\
ICM Satellite Conference \\
Institut f\"ur Algebra und Geometrie\\
Fakult\"at f\"ur Mathematik\\
Otto-von-Guericke-Universit\"at Magdeburg\\
D-39016 Magdeburg, Germany \\
{\bf email:} icmsat98(at-sign)uni-magdeburg.de
\end{document}
Date: Fri, 24 Oct 1997 10:16:07 -0400 (EDT)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: Seminar today
*********Combinatorics Seminar Today at 4:15 in 2-338**********
refreshments served at 3:45
Date: Friday, October 24, 1997
Speaker: V. Lakshmibai (Northeastern University)
Title: Tangent Spaces to Schubert Varieties
Abstract:
Let G be a classical group, T a maximal torus in G, and B a Borel
sub group containing T. Let X be any Schubert variety in G/B, and let v be
any T-fixed point in X. We give an explicit description of the tangent
space to X at v.
Upcoming events:
Date: Wednesday, October 29, 1997
Speaker: Open Mike Day
Title: (hosted by Jim Propp)
Date: Friday, October 31, 1997
Speaker: Robin PEMANTLE
Title: Linear recursions in two variables
Date: Wednesday, November 5, 1997
Speaker: James Haglund
Title: $q$-Rook polynomials and matrices over finite fields
Date: Friday, November 7, 1997
Speaker: Rod Canfield
Title: Maximum Sized Antichains in the Partition Lattice
Date: Wednesday, November 12, 1997
Speaker: Steve Fisk
Title: Interlacing Polynomials
Date: Friday, November 14, 1997
Speaker: Ludwig Danzer (University of Dortmund)
Title:Some Theorems About Strictly Ordered but Aperiodic
Structures in Euclidean Spaces
Date: Wednesday, November 19, 1997
Speaker: Sara Billey (MIT)
Title: Pattern Avoidance and Rational Smoothness of Schubert Varieties
Date: Friday, November 21, 1997
Speaker: Christos Athanasiadis
Title: Projections of cyclic polytopes and their fiber polytopes
Date: Wednesday, November 26, 1997
**Holiday--No seminar**
Date: Friday, November 28, 1997
**Holiday--No seminar**
Date: Fri, 24 Oct 1997 20:27:47 -0500
To: kcollins(at-sign)mail.wesleyan.edu
From: kcollins(at-sign)wesleyan.edu (Karen L. Collins)
Come to the Twenty-seventh one day conference on
Combinatorics and Graph Theory
Saturday, November 15, 1997
10 a.m. to 4:30 p.m.
at
Smith College
Northampton MA 01063
Schedule
10:00 Katalin Vesztergombi (Yale University)
Properties of Distance-Graphs
11:10 Charles Colbourn (Univ. of Vermont)
Group Testing and Weakly Union-free Designs
12:30 Lunch
2:00 Joel Spencer (New York University--Courant Institute)
Sixty Years of Ramsey R(3,k)
3:10 Dan Rockmore (Dartmouth College)
TBA
The conferences are supported by an NSF grant which allows us
to provide a modest transportation allowance to those attendees
who are not local. We also gratefully acknowledge support from
Smith College and Wesleyan University.
Our Web page site has directions to Smith College, abstracts of
speakers, dates of future conferences, and other information.
The address is: http://math.smith.edu/~rhaas/coneweb.html
Michael Albertson (Smith College), (413) 585-3865,
albertson(at-sign)math.smith.edu
Karen Collins (Wesleyan University), (860) 685-2169,
kcollins(at-sign)wesleyan.edu
Ruth Haas (Smith College), (413) 585-3872,
rhaas(at-sign)math.smith.edu
From: elias(at-sign)theory.lcs.mit.edu (Peter Elias)
Date: Wed, 29 Oct 97 11:16:54 EST
To: eecsfaculty(at-sign)eecs.mit.edu, seminars(at-sign)lcs.mit.edu, ai-tech-sq(at-sign)ai.mit.edu,
joanne(at-sign)theory.lcs.mit.edu, sgreen(at-sign)ll.mit.edu, jsweeney(at-sign)draper.com,
young(at-sign)lids.mit.edu, msgs(at-sign)media.mit.edu, jc(at-sign)cs.brandeis.edu,
texasgal(at-sign)MIT.EDU, bru(at-sign)media.mit.edu, arthurs(at-sign)MIT.EDU, dougross(at-sign)MIT.EDU,
msgs(at-sign)media.mit.edu, rpindyck(at-sign)MIT.EDU, or_faculty(at-sign)MIT.EDU,
combinatorics(at-sign)math.mit.edu
Subject: EECS Colloquium November 3
Please forward and/or post as appropriate.
----------------------------------------------------------------------
FACTOR GRAPHS AND ALGORITHMS:
CONNECTING BELIEF PROPAGATION TO THE FFT
AND TURBO DECODING
Frank Kschischang
University of Toronto, visiting EECS and RLE
Abstract
A "factor graph" is a bipartite graph that expresses how a global
function of several variables factors into a product of "local
functions". In this talk, I will describe a general algorithm for
computing "marginals" of the global function by distributed
message-passing in the corresponding factor graph.
A wide variety of algorithms developed in the artificial intelligence,
statistics, signal processing, and digital communications communities
can be derived as specific instances of this general algorithm,
including Pearl's "belief propagation" algorithm, the Fast Fourier
transform, the Viterbi algorithm, the forward/backward algorithm, and
the iterative turbo decoding algorithm.
November 3, 1997
4-5 pm
refreshments 3:45
Edgerton Hall, (MIT room Room 34-101, 50 Vassar St.)
======================================================================
Date: Wed, 29 Oct 1997 13:26:39 -0500 (EST)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: seminar today
*********Combinatorics Seminar Today at 4:15 in 2-338**********
refreshments served at 3:45
Date: Wednesday, October 29, 1997
Title: Open Mike Day
Speaker: (hosted by Jim Propp)
Any and all combinatorialists are invited to prepare a short 5-15
minute presentation on a resent result or open problem. Those who are
interested in speaking should send e-mail to Jim Propp
(propp(at-sign)math.mit.edu) ahead of time. Hopefully, everyone who wants to
speak will get a chance.
Upcoming events:
Date: Friday, October 31, 1997
Speaker: Robin PEMANTLE
Title: Linear recursions in two variables
Date: Wednesday, November 5, 1997
Speaker: James Haglund
Title: $q$-Rook polynomials and matrices over finite fields
**Preprint Available*** http://www-math.mit.edu/~combin/
Date: Friday, November 7, 1997
Speaker: Rod Canfield
Title: Maximum Sized Antichains in the Partition Lattice
**Preprint Available*** http://www-math.mit.edu/~combin/
Date: Wednesday, November 12, 1997
Speaker: Steve Fisk
Title: Interlacing Polynomials
Date: Friday, November 14, 1997
Speaker: Ludwig Danzer (University of Dortmund)
Title:Some Theorems About Strictly Ordered but Aperiodic
Structures in Euclidean Spaces
From: Sara Billey <sara(at-sign)math.mit.edu>
Date: Fri, 31 Oct 1997 10:53:17 -0500 (EST)
To: combinatorics(at-sign)math.mit.edu
Subject: seminar today
*********Combinatorics Seminar Today at 4:15 in 2-338**********
refreshments served at 3:45
Date: Friday, October 31, 1997
Speaker: Robin PEMANTLE
Title: Linear recursions in two variables
Let a(i,j) be real numbers for i , j > 0, satisfying
a recursion Sum a(i-r,j-s) c(r,s) = 0 for all but finitely
many (i,j), where phi (x,y) := Sum c(r,s) x^r y^s is a
given polynomial. The problem of determining asymptotics
for a(i,j) is more complicated than in the one variable
case for two reasons. First, in the case where phi(0,0) = 0,
the generating function is not rational, and some care is
needed in obtaining it. Secondly, obtaining asymptotics
from the generating function is not nearly so straightforward
as it is in the one variable case. I will discuss both
these problems, give examples, some motivation, and
partial solutions. This is work in progress.
Upcoming Events:
Date: Wednesday, November 5, 1997
Speaker: James Haglund
Title: $q$-Rook polynomials and matrices over finite fields
**Preprint Available*** http://www-math.mit.edu/~combin/
Date: Friday, November 7, 1997
Speaker: Rod Canfield
Title: Maximum Sized Antichains in the Partition Lattice
**Preprint Available*** http://www-math.mit.edu/~combin/
Date: Wednesday, November 12, 1997
Speaker: Steve Fisk
Title: Interlacing Polynomials
Date: Friday, November 14, 1997
Speaker: Ludwig Danzer (University of Dortmund)
Title:Some Theorems About Strictly Ordered but Aperiodic
Structures in Euclidean Spaces
Date: Sat, 1 Nov 1997 09:18:33 -0500
To: kcollins(at-sign)mail.wesleyan.edu
From: kcollins(at-sign)wesleyan.edu (Karen L. Collins)
Subject: November 15, second announcement
Come to the Twenty-seventh one day conference on
Combinatorics and Graph Theory
Saturday, November 15, 1997
10 a.m. to 4:30 p.m.
at
Smith College
Northampton MA 01063
Schedule
10:00 Katalin Vesztergombi (Yale University)
Properties of Distance-Graphs
11:10 Charles Colbourn (Univ. of Vermont)
Group Testing and Weakly Union-free Designs
12:30 Lunch
2:00 Joel Spencer (New York University--Courant Institute)
Sixty Years of Ramsey R(3,k)
3:10 Dan Rockmore (Dartmouth College)
FFTs for $SL_2(F_q)$ - Theory and Applications
The conferences are supported by an NSF grant which allows us
to provide a modest transportation allowance to those attendees
who are not local. We also gratefully acknowledge support from
Smith College and Wesleyan University.
Our Web page site has directions to Smith College, abstracts of
speakers, dates of future conferences, and other information.
The address is: http://math.smith.edu/~rhaas/coneweb.html
Michael Albertson (Smith College), (413) 585-3865,
albertson(at-sign)math.smith.edu
Karen Collins (Wesleyan University), (860) 685-2169,
kcollins(at-sign)wesleyan.edu
Ruth Haas (Smith College), (413) 585-3872,
rhaas(at-sign)math.smith.edu
Date: Mon, 3 Nov 1997 14:32:36 -0500 (EST)
From: Combinatorics Conference <calca(at-sign)Oakland.edu>
To: calca(at-sign)Oakland.edu
Subject: Conference Annoucement
=================================================================================================
FIRST ANNOUNCEMENT
Conference on Algebraic Combinatorics and Applications
Oakland University, Rochester, Michigan
May 1-3, 1998
Invited one-hour speakers include
Anders Bjorner (Royal Institute of Technology, Stockholm)
Robert Calderbank (AT&T Research)
Peter Cameron (Queen Mary College, London)
Jennifer Chayes (Microsoft)
Philippe Flajolet (INRIA)
Ronald Graham (AT&T Research)
David Jackson (University of Waterloo)
Richard Stanley (MIT)
There will also be sessions for invited half-hour talks;
speakers currently include Georgia Benkart, Nantel Bergeron, Sara Billey,
Aart Blokhuis, Aldo Conca, Sergey Fomin, Bernard Leclerc, Victor Reiner,
John Stembridge, Neil White and Charles Johnson..
Persons in academia or industry interested in exploring this fertile and
evolving area of mathematics and its interactions with and applications to
other areas are encouraged to participate. Some support will be available
to assist graduate students in attending the conference.
Sponsors include the National Science Foundation, the National Security
Agency, Oakland University, the Oakland University Foundation, and others
still pending.
Anyone interested in further information should send name, institution,
e-mail address, and current estimated probability of attending, to the
organizers by e-mail or snail-mail.
Conference e-mail address: calca(at-sign)oakland.edu
Conference home page on the World Wide Web:
http://www.oakland.edu/~calca
Organizing Committee
Eddie Cheng (Oakland University)
Ian Goulden (University of Waterloo)
Jerrold Grossman (Oakland University), Local Arrangements Chair
(248) 370-3443 grossman(at-sign)oakland.edu
Philip Hanlon (University of Michigan)
Devadatta Kulkarni , Director
(248) 370-4032 kulkarni(at-sign)oakland.edu
Marc Lipman (Oakland University)
James McKay (Oakland University)
Conference on Algebraic Combinatorics and Applications
Department of Mathematical Sciences
Oakland University
Department of Mathematical Sciences
Oakland University
Rochester, MI 48309-4485
Date: Mon, 3 Nov 1997 16:17:42 -0500 (EST)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu, combinatorics(at-sign)euclid.ucsd.edu
Subject: [bdt(at-sign)math.wayne.edu: jobs in combinatorics]
Date: Mon, 3 Nov 1997 16:11:06 -0500
From: bdt(at-sign)math.wayne.edu (Brian Taylor)
To: sara(at-sign)math.mit.edu
Subject: jobs in combinatorics
------------------------------------------------------------------
The Wayne State University mathematics department is hiring for
two tenure-track positions this year. One of these is an open
position for which we could hire an algebraic combinatorialist.
In particular, the algebra group here is committed to hiring
another algebraic combinatorialist within the next several years.
Please feel free to ask me unofficial questions about the
department or Detroit at "bdt(at-sign)math.wayne.edu".
For official information, check our (slightly old) notice on EIMS.
Brian Taylor
------------------------------------------------------------------
Date: Wed, 5 Nov 1997 12:55:41 -0500 (EST)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: seminar today
*********Combinatorics Seminar Today at 4:15 in 2-338**********
refreshments served at 3:45
Date: Wednesday, November 5, 1997
Speaker: James Haglund
Title: $q$-Rook polynomials and matrices over finite fields
**Preprint Available*** http://www-math.mit.edu/~combin/
Abstract: We start by giving a brief overview of the basics of rook
theory and q-rook polynomials. Then we extend a result of Solomon,
which shows that q-rook polynomials count the number of matrices over
finite fields satisfying certain constraints. This eventually leads
to a new statistic for Garsia and Remmel's q-hit polynomial. Both
this new statistic "mat" and another statistic for the q-hit
polynomial \xi recently introduced by Dworkin are shown to induce
different multiset Mahonian permutation statistics for any Ferrers
board. In addition, for the triangular boards they are shown to
generate different families of Euler-Mahonian statistics. For these
boards the \xi family includes Denert's statistic "den", and gives a
new proof of Foata and Zeilberger's Theorem that (exc,den) is
equi-distributed with (des,maj). The mat family appears to generate a
new Euler-Mahonian pair. A proof that the q-hit polynomials are
symmetric and unimodal is also discussed.
Upcoming Events:
Date: Friday, November 7, 1997
Speaker: Rod Canfield
Title: Maximum Sized Antichains in the Partition Lattice
**Preprint Available*** http://www-math.mit.edu/~combin/
Date: Wednesday, November 12, 1997
Speaker: Steve Fisk
Title: Interlacing Polynomials
Date: Friday, November 14, 1997
Speaker: Ludwig Danzer (University of Dortmund)
Title:Some Theorems About Strictly Ordered but Aperiodic
Structures in Euclidean Spaces
Date: Fri, 7 Nov 1997 13:03:34 -0500 (EST)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: seminar today
*********Combinatorics Seminar Today at 4:15 in 2-338**********
refreshments served at 3:45
Date: Friday, November 7, 1997
Speaker: Rod Canfield
Title: Maximum Sized Antichains in the Partition Lattice
**Preprint Available*** http://www-math.mit.edu/~combin/
Abstract:
In 1928 E. Sperner solved this problem: Given a finite
ground set S of size n, what is the largest possible collection of
subsets of S such that no two of the subsets are related by containment?
In the last twenty years, a generalization of this problem has
been studied, namely: given a finite partially ordered set (poset), what
is its largest antichain? (An antichain is a set of elements no two
of which are related by the poset's order relation.)
Many interesting posets arise naturally in combinatorics, one of
which is partitions of an n-set ordered by refinement. A partition
of the n-set [n] = {1,2,...,n} is a collection of pairwise disjoint
subsets, called blocks, whose union is [n]. One partition is a
refinement of another if the first can be obtained by further
partitioning the blocks of the second.
Determining the size of the largest antichain in this partition poset
has spawned many general theorems in the subject now known as Sperner
Theory. We will trace the study of large antichains in the partition
lattice.
Upcoming Events:
Date: Wednesday, November 12, 1997
Speaker: Steve Fisk
Title: Interlacing Polynomials
Date: Friday, November 14, 1997
Speaker: Ludwig Danzer (University of Dortmund)
Title:Some Theorems About Strictly Ordered but Aperiodic
Structures in Euclidean Spaces
Date: Fri, 7 Nov 1997 18:01:07 -0400
To: Everyone(at-sign)mathstat.yorku.ca
From: bergeron(at-sign)mathstat.yorku.ca (Nantel Bergeron)
Subject: FPSAC 98 --- SECOND CALL FOR PAPERS
% ********************************************************************** %
% %
% 10-th international Conference on %
% Formal Power Series and Algebraic Combinatorics %
% %
% June 15-19, 1998 %
% Fields Institute, Toronto %
% %
% First announcement -- Call for papers %
% %
% ********************************************************************** %
TOPICS: Algebraic and bijective combinatorics and their relations with
other parts of mathematics, computer science and physics.
CONFERENCE PROGRAM: Invited lectures, contributed presentations,
poster session, software demonstrations.
INVITED SPEAKERS:
G. Benkart (USA)
P. Cameron (England) (to be confirmed)
P. Dehornoy (France)
B. Derrida (France) (to be confirmed)
P. Diaconis (USA)
C. Godsil (Canada)
K. Ono (USA)
J. Y. Thibon (France)
B. Sturmfels (USA)
OFFICIAL LANGUAGES: English and French.
CALL FOR PAPERS AND POSTERS: Authors are invited to submit extended
abstracts of at most twelve pages before
November 21, 1997.
------------------
Authors should indicate their choice of presentation appropriate for their
paper: lecture or poster session. The preferred method of submission is by
sending one postscript file by email to
bergeron(at-sign)mathstat.yorku.ca.
If an author is not able to send a postscript version of her/his extended
abstract, four copies of the extended abstract should be mailed to
Nantel Bergeron, Program committee of FPSAC '98
Department of Mathematics and Statistics 61
York University
4700 Keele St.
North York, Ontario, Canada, M3J 1P3.
The submitted papers should begin with a summary written in the two
official languages of the conference (translations will be provided
if necessary). The notifications of acceptance or rejection are scheduled
for the beginning of March 1998.
Published Volume:
The authors whose papers will have been accepted for a lecture or a
poster presentation will have the possibility to submit a complete
version of their work to a special issue of a refereed publication
devoted to the conference FPSAC '98. The deadline for
submission to the special issue is September 1, 1998.
SOFTWARE DEMONSTRATIONS: Demonstrations of software relevant to the
topics of the conference are encouraged. People interested in giving
a software demonstration should submit a paper as described above,
including the hardware requirements, before January 15, 1997,
by email to
sottile(at-sign)math.toronto.edu.
PROGRAM COMMITTEE:
I. Goulden, Chairman (Canada), N. Bergeron (Canada),
S. Billey (USA), F. Brenti (Italy), R. Cori (France), S. Dulucq (France)
K. Eriksson (Sweeden), O. Foda (Australia), S. Fomin (USA/Russia),
I. Gessel (USA), C. Greene (USA), A. Hamel (New Zealand), D. Kim (Korea),
C. Krattenthaler (Austria), D. Krob (France), M. Noy (Spain), V. Reiner (USA),
C. Reutenauer (UQAM), F. Sottile (U. Toronto), T. Visentin (U. Winnipeg).
M. Wachs (USA), H. Yamada (Japan), G. Ziegler (Germany).
For more Information on registration and support, consult the WWW site
http://www.math.yorku.ca/bergeron
or email
bergeron(at-sign)mathstat.yorku.ca.
ORGANIZING COMMITTEE
N. Bergeron, Chairman (York U.), M. Delest (U. de Bordeaux),
F. Sottile (U. Toronto), W. Whiteley (York U.).
Nantel Bergeron bergeron(at-sign)mathstat.yorku.ca
Associate Prof. Mathematics nantel(at-sign)math.harvard.edu
York University nantel(at-sign)lacim.uqam.ca
http://www.math.yorku.ca/bergeron
Date: Tue, 11 Nov 1997 12:59:02 -0400
To: frank sottile <sottile(at-sign)math.utoronto.ca>, combinatorics(at-sign)cs.toronto.edu,
combopt(at-sign)math.uwaterloo.ca, combinatorics(at-sign)math.mit.edu,
combinatorics(at-sign)euclid.ucsd.edu, everyone(at-sign)mathstat.yorku.ca,
deaconu(at-sign)YorkU.CA, JOAQUIN O CARBONARA <CARBONJO(at-sign)BUFFALOSTATE.EDU>
From: bergeron(at-sign)mathstat.yorku.ca (Nantel Bergeron)
Subject: York U. Applied Algebra Seminar: Y. Medvedev
Announcement: A web page at "http://math.yorku.ca/bergeron" is set up
for this new seminar. Please look at it if you are interested.
Suggestions are welcome.
--------------------------------------------------------------------------
Next week:
Applied Algebra Seminar
York University
Ross Building, North tower: N638R
Monday Nov. 17, 1997
3:00 PM
--------------------------------------------------------------------------
Compact Periodic and Engel Groups
Yuri Medvedev
York U.
The question whether a compact periodic group has a finite exponent has been
known since early 60's. One can find a discussion on this question in the book
on Abstract Harmonic Analysis by Hewitt and Ross. Recently, Zelmanov,
developing his ideas on the solution of the restricted Burnside problem, has
proved that compact periodic groups are locally finite. Hence, every Sylow
p-subgroup of compact periodic groups are Engel. I will give an outline of an
approach which leads to a necessary and sufficient condition for a periodic
compact group to be of finite exponent. It turned out that a periodic compact
group has a finite exponent if and only if it is strongly Engel. As usual, we
will talk about open problems in this area.
--------------------------------------------------------------------------
FORTHCOMING SEMINARS:
A. Kirrilov (CRM-St Petersburg) (Nov/Dec)
S. Van Willigenburg (York/St Andrews) (Dec)
A. Ram (Princeton) (Jan 98)
ANY OTHER SUGGESTION? (email me!)
Nantel Bergeron bergeron(at-sign)mathstat.yorku.ca
Associate Prof. Mathematics nantel(at-sign)math.harvard.edu
York University nantel(at-sign)lacim.uqam.ca
http://www.math.yorku.ca/bergeron
Date: Wed, 12 Nov 1997 10:12:45 -0500
To: kcollins(at-sign)mail.wesleyan.edu
From: kcollins(at-sign)wesleyan.edu (Karen L. Collins)
Subject: reminder
Come to the Twenty-seventh one day conference on
Combinatorics and Graph Theory
Saturday, November 15, 1997
10 a.m. to 4:30 p.m.
at
Smith College
Northampton MA 01063
Schedule
10:00 Katalin Vesztergombi (Yale University)
Properties of Distance-Graphs
11:10 Charles Colbourn (Univ. of Vermont)
Group Testing and Weakly Union-free Designs
12:30 Lunch
2:00 Joel Spencer (New York University--Courant Institute)
Sixty Years of Ramsey R(3,k)
3:10 Dan Rockmore (Dartmouth College)
FFTs for $SL_2(F_q)$ - Theory and Applications
The conferences are supported by an NSF grant which allows us
to provide a modest transportation allowance to those attendees
who are not local. We also gratefully acknowledge support from
Smith College and Wesleyan University.
Our Web page site has directions to Smith College, abstracts of
speakers, dates of future conferences, and other information.
The address is: http://math.smith.edu/~rhaas/coneweb.html
Michael Albertson (Smith College), (413) 585-3865,
albertson(at-sign)math.smith.edu
Karen Collins (Wesleyan University), (860) 685-2169,
kcollins(at-sign)wesleyan.edu
Ruth Haas (Smith College), (413) 585-3872,
rhaas(at-sign)math.smith.edu
Date: Wed, 12 Nov 1997 15:04:40 -0500 (EST)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: seminar today
*********Combinatorics Seminar Today at 4:15 in 2-338**********
refreshments served at 3:45
Date: Wednesday, November 12, 1997
Speaker: Steve Fisk
Title: Interlacing Polynomials
Two polynomials interlace if their roots alternate. The central
question in the study of interlacing is
When does a linear transformation on the vector space of all polynomials
preserve interlacing?
In this talk I will discuss various interlacing preserving linear
transformations. For instance, differentiation preserves interlacing,
but integration does not.
It is a classical result that if f and g are polynomials with all real
roots then f(D)g has all real roots, where D is differentiation. I
will show that the bilinear map sending (f,g) to f(D)g preserves
interlacing in each argument.
Upcoming Events:
Date: Friday, November 14, 1997
Speaker: Ludwig Danzer (University of Dortmund)
Title:Some Theorems About Strictly Ordered but Aperiodic
Structures in Euclidean Spaces
Date: Fri, 14 Nov 1997 12:07:43 -0500 (EST)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: seminar today
*********Combinatorics Seminar Today at 4:15 in 2-338**********
refreshments served at 3:45
Date: Friday, November 14, 1997
Speaker: Ludwig Danzer (University of Dortmund)
Title:Some Theorems About Strictly Ordered but Aperiodic
Structures in Euclidean Spaces
Let F be a finite set of prototiles T_1, T_2,...,T_k. An F-tiling is a
global tiling of euclidean space, where every tile is congruent to some
T_{\kappa}. If Infl is an inflation-operator, then S(F,Infl) is the
"species" of all F-tilings P such that every bounded cluster of P has a
congruent copy in some Infl^n (T_{\kappa}). If LMR is a local matching
rule, then S(F, LMR) is the species of all F-tilings which satisfy LMR
everywhere.
The relationships between the following properties of such species
will be discussed:
-- (I) being definable by some inflation,
-- (D) existence of a unique inverse of Infl,
-- (LMR) being definable by some local matching rule,
-- (AP) being aperiodic,
-- (NL) being non-local (not in contradiction to (LMR) !),
-- (R) being repetitive,
-- consisting of 2^{\aleph_0} congruence classes.
*******************************************************************
The following talk has been rescheduled for February 27:
Speaker: Sara Billey (MIT)
Title: Pattern Avoidance and Rational Smoothness of Schubert Varieties
**Preprint Available*** http://www-math.mit.edu/~sara/
No seminar: Wednesday, November 19, 1997
*******************************************************************
Upcoming events:
Date: Friday, November 21, 1997
Speaker: Christos Athanasiadis
Title: Projections of cyclic polytopes and their fiber polytopes
Date: Wednesday, November 26, 1997
**Holiday--No seminar**
Date: Friday, November 28, 1997
**Holiday--No seminar**
Date: Fri, 14 Nov 1997 14:25:29 -0500
To: kcollins(at-sign)mail.wesleyan.edu
From: kcollins(at-sign)wesleyan.edu (Karen L. Collins)
Subject: cancellation
Smith College is closing today due to a storm depositing sleet,
ice and snow on campus. The storm is expected to continue through
the weekend. We therefore regret that twenty-seventh CoNE meeting,
scheduled for tomorrow, November 15, must be cancelled.
Date: Tue, 18 Nov 1997 15:56:32 -0400
To: bergeron(at-sign)mathstat.yorku.ca
From: bergeron(at-sign)mathstat.yorku.ca (Nantel Bergeron)
Subject: York U. Applied Algebra Seminar: S. van Willigenburg
Announcement: A web page at "http://math.yorku.ca/bergeron" is set up
for this new seminar. Look for our future seminars.
Suggestions are welcome.
--------------------------------------------------------------------------
Next week:
Applied Algebra Seminar
York University
Ross Building, North tower: N638R
Monday Nov. 24, 1997
3:00 PM
--------------------------------------------------------------------------
The p-modular descent algebra of the symmetric group
Stephanie van Willigenburg
(St-Andrews/ York University)
Abs: We define the descent algebra of the symmetric group over the rationals.
We then extend this definition to a field of finite characteristic. From here
we discuss why these structures are of interest, and formulate one of the many
open problems in this area.
--------------------------------------------------------------------------
FORTHCOMING SEMINARS:
N. Bergeron (York) (Dec 1)
A. Kirrilov (CRM-St Petersburg) (Dec 8-9)
A. Ram (Princeton) (Jan 98)
ANY OTHER SUGGESTION? (email me!)
Nantel Bergeron bergeron(at-sign)mathstat.yorku.ca
Associate Prof. Mathematics nantel(at-sign)math.harvard.edu
York University nantel(at-sign)lacim.uqam.ca
http://www.math.yorku.ca/bergeron
Date: Wed, 19 Nov 1997 12:05:02 -0500 (EST)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: seminar today
There has been a change of plans. There will be a seminar today.
*********Combinatorics Seminar Today at 4:15 in 2-338**********
refreshments served at 3:45
Date: Wednesday, November 19, 1997
Speaker: J. Maurice Rojas (MIT)
Title: The Square Root Volume Conjecture
Preprint:http://www-math.mit.edu/~combin/preprints/Rojas97.ps
Abstract:
Shub and Smale showed that for certain random polynomial
systems, the expected number of real roots equals the square root of the
expected number of complex roots. We prove a similar theorem for a new
family of polynomial systems and propose a broader conjecture --- the
square root volume conjecture (SRVC).
The class of sparse polynomial systems where the SRVC
has been proved also includes randomized versions of the
following well-known problems from linear algebra:
the generalized eigenvalue problem and the matrix polynomial
problem.
Our probability measures can all be described via convex
geometry, and are natural in a metrically invariant sense, depending
on the underlying toric compactification. This talk will be
entirely self-contained (no knowledge of toric varieties is
assumed).
Upcoming Events:
Date: Friday, November 21, 1997
Speaker: Christos Athanasiadis
Title: Projections of cyclic polytopes and their fiber polytopes
Date: Wednesday, November 26, 1997
**Holiday--No seminar**
Date: Friday, November 28, 1997
**Holiday--No seminar**
December is available at http://www-math.mit.edu/~combin/abstracts.
Date: Wed, 19 Nov 1997 15:42:06 -0500
To: kcollins(at-sign)mail.wesleyan.edu
From: kcollins(at-sign)wesleyan.edu (Karen L. Collins)
Subject: New meeting!
Come to the (New) Twenty-seventh one day conference on
Combinatorics and Graph Theory
Saturday, December 13, 1997
10 a.m. to 4:30 p.m.
at
Smith College
Northampton MA 01063
Schedule
10:00 James Lewis (Univ. of Rhode Island)
A Collatz Type Difference Equation
11:10 Jeffrey Hall (Univ. of New Hampshire)
Applications of Combinatorics to
Group Representation Theory
12:10 Lunch
2:00 Charles Colbourn (Univ. of Vermont)
Group Testing and Weakly Union-free Designs
3:10 Karen Collins (Wesleyan University)
TBA
The conferences are supported by an NSF grant which allows us
to provide a modest transportation allowance to those attendees
who are not local. We also gratefully acknowledge support from
Smith College and Wesleyan University.
Our Web page site has directions to Smith College, abstracts of
speakers, dates of future conferences, and other information.
The address is: http://math.smith.edu/~rhaas/coneweb.html
Michael Albertson (Smith College), (413) 585-3865,
albertson(at-sign)math.smith.edu
Karen Collins (Wesleyan University), (860) 685-2169,
kcollins(at-sign)wesleyan.edu
Ruth Haas (Smith College), (413) 585-3872,
rhaas(at-sign)math.smith.edu
Date: Fri, 21 Nov 1997 13:57:16 -0500 (EST)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: seminar today
*********Combinatorics Seminar Today at 4:15 in 2-338**********
refreshments served at 3:45
Date: Friday, November 21, 1997
Speaker: Christos Athanasiadis
Title: Projections of cyclic polytopes and their fiber polytopes
Given any affine projection of polytopes P --> Q, Billera and Sturmfels
have defined a new polytope, called the fiber polytope of the projection.
Its faces correspond to certain induced polytopal subdivisions of Q,
called coherent subdivisions. We consider the cyclic polytopes C(n,d),
having n vertices on the d-dimensional moment curve, and the canonical
projections C(n,d) --> C(n,d') between them. We show that for d'=1, the
corresponding fiber polytope has combinatorial structure that is independent
of the coordinates used to define C(n,d), namely that of a zonotope with
n-2 generators on the (d-1)-dimensional moment curve. We show that the
combinatorics of the fiber polytope may vary along with the parameters as
soon as d' is at least 2 and classify all triples (n,d,d') for which the
property of coherence is independent of the coordinates for any induced
subdivision of C(n,d'). This is joint work with Jesu's DeLoera, Victor
Reiner and Francisco Santos.
Date: Wednesday, November 26, 1997
**Holiday--No seminar**
Date: Friday, November 28, 1997
**Holiday--No seminar**
Date: Wednesday, December 3, 1997
Speaker: Vesselin Gasharov
Title: Convexity and A-Graded Algebras
Date: Friday, December 5, 1997
Speaker: Dmitry Kozlov (MIT)
Title:Group action on posets
Date: Wednesday, December 10, 1997
Speaker: Jesus Deloera (Geometry Institute)
Title: Remarks on Viro's combinatorial construction of smooth real
projective hypersurfaces
**This will be the last talk of the year.
Date: Wed, 26 Nov 1997 10:38:11 +0100
To: (Recipient list suppressed)
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Date: Wed, 26 Nov 1997 15:23:26 -0500
To: kcollins(at-sign)mail.wesleyan.edu
From: kcollins(at-sign)wesleyan.edu (Karen L. Collins)
Subject: Job advertisement from CUNY/CSI
Deborah Franzblau would like to make everyone aware of
the following opportunities at CUNY.
********************************************************
College of Staten Island
City University of New York (CUNY)
Department of Mathematics
New Tenure-track Positions
The College of Staten Island (CSI) Department of
Mathematics invites applications for two new tenure-track
assistant professorships, to begin September, 1998. CSI, a
four-year senior college of the City University of New York
(CUNY), has a newly renovated campus, which is convenient
to the many colleges and research centers in central New
Jersey and New York City. The department, which has 22
full-time faculty members, offers B.S. degrees in
mathematics, math/cs, and math/education, and graduate-
level mathematics courses for secondary-school teachers.
Further information about the department and CSI can be
found at http://www.library.csi.cuny.edu/dept/math.
We seek candidates with outstanding research potential and
productive research programs, who are also excellent teachers
committed to undergraduate education. A Ph.D. is required,
and postdoctoral experience is desirable. One position is
open to those with experience in interdisciplinary research,
who will contribute to a college-wide initiative for research
and education in interdisciplinary applied mathematics. The
other position is open to candidates in all fields of
mathematics, who have a demonstrated interest in
applications. Salaries range from approximately $34K to
$52K. Qualified candidates may be nominated for
appointment to the CUNY doctoral faculty.
To apply, send an AMS cover sheet, a vita, a short description
of current and planned research, and a short statement on
teaching experience and philosophy. At least three letters of
recommendation should be sent separately. Mail all materials
to Faculty Search, Prof. Bruce Chandler, Chair, Dept. of
Mathematics (1S-215), College of Staten Island, 2800 Victory
Blvd., Staten Island, NY 10314. If you will attend the
Mathematics Meetings in Baltimore this January, please let
us know the dates that you will be there. To ensure full
consideration, all materials must be received by January 30,
1998. CSI is an EO/AA Employer, and is committed to
maintaining a diverse faculty.
Date: Sun, 30 Nov 1997 11:34:12 -0500
From: blaw(at-sign)fields.utoronto.ca (Brenda Law)
To: fpart(at-sign)fields.utoronto.ca
Subject: Conference Announcement
The Fields Institute
Centre de recherches mathématiques
First Announcement
10th International Conference on
Formal Power Series and Algebraic Combinatorics
Sunday, June 14 to Friday, June 19, 1998
to be held at
The Fields Institute, Toronto, Canada
INVITED SPEAKERS
G. Benkart (USA) P. Cameron (England) P. Dehornoy (France)
B. Derrida (France) P. Diaconis (USA) C. Godsil (Canada)
K. Ono (USA) B. Sturmfels (USA) J.-Y. Thibon ( France)
Organizing Committee
N. Bergeron, Chairman (Canada)
M. Delest (France)
F. Sottile (Canada)
W. Whiteley (Canada)
Program Committee
I. Goulden, Chairman (Canada)
N. Bergeron (Canada)
S. Billey (USA)
F. Brenti (Italy)
R. Cori (France)
S. Dulucq (France)
K. Eriksson (Sweden)
O. Foda (Australia)
S. Fomin (USA/Russia)
I. Gessel (USA)
C. Greene (USA)
A. Hamel (New Zealand)
D. Kim (Korea)
C. Krattenthaler (Austria)
D. Krob (France)
M. Noy (Spain)
V. Reiner (USA)
C. Reutenauer (Australia)
F. Sottile (Canada)
T. Visentin (Canada)
M. Wachs (USA)
H. Yamada (Japan)
G. Ziegler (Germany)
TOPICS: Algebraic and bijective combinatorics and their relations
with other parts of mathematics, computer science and physics.
CONFERENCE PROGRAM: Invited lectures, contributed presentations,
poster sessions and software demonstrations.
CALL FOR PAPERS AND POSTERS: Authors are invited to submit
extended abstracts of at most 12 pages before November 30, 1997. Authors
should indicate their choice of presentation appropriate for
their paper: lecture or poster session. To submit: The preferred method
of submission is by sending one postscript file by email
to fpsac98(at-sign)fields.utoronto.ca. If an author is not able to
send a postscript version of the extended abstract, four copies should
be mailed to the Fields Institute at the address below. Papers
should begin with a summary written in the two official languages of
the conference (translations will be provided if necessary). The
notifications of acceptance or rejection are scheduled for
the beginning of March 1998.
Published Volume: The authors whose papers will have
been accepted for a lecture or a poster presentation may be
invited to submit a complete version of their work to a
special issue of a refereed publication, devoted to
the conference FPSAC '98. The deadline for submission
to the special issue is September 1, 1998.
SOFTWARE DEMONSTRATIONS: Demonstrations of software
relevant to the topics of the conference are encouraged. People
interested in giving a software demonstration should submit a
short description of the software, including the
hardware requirements, before
January 15, 1998, by email to fsottile(at-sign)fields.utoronto.ca.
PARTICIPANT SUPPORT: Limited funds are available for partial
support of participants. Requests should contain a letter
of recommendation and include the estimated transportation
and living expenses as well as the amount of support
available from other sources. All requests should be
sent in duplicate by January 15, 1998 to the Fields Institute.
REGISTRATION: Until April 15, 1998, the registration fee
is $200 and $100 is offered for students (with verification,
such as a letter from the advisor). After April 15, 1998 fees
will be $300 and $150, respectively. The registration fee
covers all lectures and presentations, program materials,
refreshment breaks, a copy of the abstract package, and a
dinner on Thursday night. Make cheques payable
to "Fields Institute/fpsac98". To register, please
contact the Fields Institute.
email: fpsac98(at-sign)fields.utoronto.ca web-site: www.fields.utoronto.ca
fax: (416) 348-9385 (on-line registration available)
Sponsored by Centre de recherches mathématiques, The Fields Institute for Research in Mathematical Sciences, University of Toronto, and York University
The Fields Institute, 222 College Street,
Toronto, Ontario, Canada M5T 3J1
Telephone: (416) 348-9710
Fax: (416) 348-9385
Date: Sun, 30 Nov 1997 15:11:19 -0500
To: kcollins(at-sign)mail.wesleyan.edu
From: kcollins(at-sign)wesleyan.edu (Karen L. Collins)
Subject: Job ad
Lauren Rose would like everyone to be aware of the following
opportunity at Bard College. Send her some e-mail at
rose(at-sign)bard.edu
if you would like more information.
*********************************************
COMPUTER SCIENCE POSITION AT BARD COLLEGE
The Division of Natural Science and Mathematics at Bard College
invites applications for a full time, tenure track position in
computer science starting in Fall 1998.
The position requires a PhD in computer science, or a PhD in mathematics
or physics and an MS in computer science. The candidate will be a core
member of the mathematics program, and possibly other programs within the
college. The ability to interact with mathematicians and other scientists
at Bard is essential. The position requires a strong commitment to
excellence in teaching, including supervising undergraduate senior
projects, and an ongoing program of scholarly activity.
The candidate will teach introductory programming classes for both science
and non-science majors, as well as upper level computer science and
computational math and/or science courses. Although there is no computer
science major at Bard, we envision the development of concentrations in
computational mathematics and physics, as well as courses to support these
concentrations.
Bard is a prestigious liberal arts college located in the Hudson Valley
region of New York, 2 hours north of NYC. Applicants should submit a
letter of application, curriculum vitae, a statement of teaching and
research interests, and 3 letters of recommendation (at least one of
which addresses teaching) to: Professor Mark Halsey, c/o Office of Human
Resources, Bard College, Annandale-on-Hudson, NY 12504. The deadline for
applications is January 1, 1998. Bard College is an equal opportunity
employer. Women and minority candidates are especially encouraged to
apply.
Date: Sun, 30 Nov 1997 15:11:00 -0500
To: kcollins(at-sign)mail.wesleyan.edu
From: kcollins(at-sign)wesleyan.edu (Karen L. Collins)
Subject: second announcement
Come to the (New) Twenty-seventh one day conference on
Combinatorics and Graph Theory
Saturday, December 13, 1997
10 a.m. to 4:30 p.m.
at
Smith College
Northampton MA 01063
Schedule
10:00 James Lewis (Univ. of Rhode Island)
A Collatz Type Difference Equation
11:10 Jeffrey Hall (Univ. of New Hampshire)
Applications of Combinatorics to
Group Representation Theory
12:10 Lunch
2:00 Charles Colbourn (Univ. of Vermont)
Group Testing and Weakly Union-free Designs
3:10 Karen Collins (Wesleyan University)
Breaking Symmetries of S5 and S6
The conferences are supported by an NSF grant which allows us
to provide a modest transportation allowance to those attendees
who are not local. We also gratefully acknowledge support from
Smith College and Wesleyan University.
Our Web page site has directions to Smith College, abstracts of
speakers, dates of future conferences, and other information.
The address is: http://math.smith.edu/~rhaas/coneweb.html
Michael Albertson (Smith College), (413) 585-3865,
albertson(at-sign)math.smith.edu
Karen Collins (Wesleyan University), (860) 685-2169,
kcollins(at-sign)wesleyan.edu
Ruth Haas (Smith College), (413) 585-3872,
rhaas(at-sign)math.smith.edu
Date: Wed, 3 Dec 1997 13:10:11 -0500 (EST)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: seminar today
*********Combinatorics Seminar Today at 4:15 in 2-338**********
refreshments served at 3:45
Date: Wednesday, December 3, 1997
Speaker: Vesselin Gasharov
Title: Convexity and A-Graded Algebras
Abstract:
Let A be a finite subset of N^d. An ideal is called A-graded if it has the
same Hilbert function as the toric ideal J defined by A. What are the
A-graded ideals? The structure of such ideals was first studied by Arnold
who related it to continued fractions. Arnold, Korkina, Post, and Roelofs
proved that if J defines an affine monomial curve in A^3, then every A-graded
ideal is an initial ideal of the toric ideal J. Later Sturmfels studied
A-graded ideals in the general case and related their structure to the
convexity properties of the set A. In particular, he showed that the
monomial A-graded ideals correspond to triangulations of the convex envelope
of A. In view of Lee's theorem that A has only regular triangulations if the
codimension is 2, Sturmfels conjectured the following generalization of the
Arnold-Korkina-Post-Roelofs result: if the toric ideal J has codimension 2,
then every A-graded ideal is an initial ideal of J. We prove this conjecture.
The proof relies on a combinatorial description of the syzygies of J. This
is a joint work with Irena Peeva.
Date: Friday, December 5, 1997
Speaker: Dmitry Kozlov (MIT)
Title:Group action on posets
Date: Wednesday, December 10, 1997
Speaker: Jesus Deloera (Geometry Institute)
Title: Remarks on Viro's combinatorial construction of smooth real
projective hypersurfaces
**This will be the last talk of the semester**
Date: Wed, 10 Dec 1997 14:16:16 -0500 (EST)
From: Sara Billey <sara(at-sign)math.mit.edu>
To: combinatorics(at-sign)math.mit.edu
Subject: seminar today
*********Combinatorics Seminar Today at 4:15 in 2-338**********
refreshments served at 3:45
Date: Wednesday, December 10, 1997
Speaker: Jesus Deloera (Geometry Institute)
Title: Remarks on Viro's combinatorial construction of smooth real
projective hypersurfaces
Abstract:
Hilbert's 16th problem is partially concerned with the classification of
topological types of smooth real projective hypersurfaces. It is
clearly important to have available effective methods to produce
examples of new topological types. During the 1980's Oleg Viro
developed a combinatorial technique for constructing hypersurfaces
with given topology. This technique has been highly succesful and it
was used by Ilia Itenberg, in 1993, to provide counterexamples to
the ninety year old Ragsdale conjecture.
Viro's construction of real smooth hypersurfaces uses regular
(also called convex or coherent) triangulations of convex polytopes.
Nevertheless, Viro's construction can also be applied as well to arbitrary
triangulations. Are the combinatorial hypersurfaces coming from
non-regular triangulations, still topological types of some real smooth
hypersurfaces? In this talk we present current advances for
the solution of this question. This is joint work with Frederick Wicklin.
**This will be the last talk of the semester.**
Have a nice vacation. We will resume on February 4th.
Date: Fri, 12 Dec 1997 13:28:59 -0500
To: kcollins(at-sign)mail.wesleyan.edu
From: kcollins(at-sign)wesleyan.edu (Karen L. Collins)
Subject: reminder about tomorrow
Come to the Twenty-seventh one day conference on
Combinatorics and Graph Theory
Saturday, December 13, 1997
10 a.m. to 4:30 p.m.
at
Smith College
Northampton MA 01063
Schedule
10:00 James Lewis (Univ. of Rhode Island)
A Collatz Type Difference Equation
11:10 Jeffrey Hall (Univ. of New Hampshire)
Applications of Combinatorics to
Group Representation Theory
12:10 Lunch
2:00 Charles Colbourn (Univ. of Vermont)
Group Testing and Weakly Union-free Designs
3:10 Karen Collins (Wesleyan University)
Breaking Symmetries of S5 and S6
The conferences are supported by an NSF grant which allows us
to provide a modest transportation allowance to those attendees
who are not local. We also gratefully acknowledge support from
Smith College and Wesleyan University.
Our Web page site has directions to Smith College, abstracts of
speakers, dates of future conferences, and other information.
The address is: http://math.smith.edu/~rhaas/coneweb.html
Michael Albertson (Smith College), (413) 585-3865,
albertson(at-sign)math.smith.edu
Karen Collins (Wesleyan University), (860) 685-2169,
kcollins(at-sign)wesleyan.edu
Ruth Haas (Smith College), (413) 585-3872,
rhaas(at-sign)math.smith.edu