Date:           Fri, 26 Jul 1996 10:37:25 -0400
To:             kcollins(at-sign)mail.wesleyan.edu
From:           kcollins(at-sign)wesleyan.edu (Karen L. Collins)
Subject:        Fall meetings


NSF renewed our grant!!  The first two CoNE meetings in 96-97
will be September 28th and October 26th.


Date:           Tue, 30 Jul 1996 19:03:52 -0400
To:             kcollins(at-sign)mail.wesleyan.edu
From:           kcollins(at-sign)wesleyan.edu (Karen L. Collins)
Subject:        job announcement


>From The Connecticut Post, Sunday, July 28, 1996
____________________________________________________

MATHEMATICS
Western Connecticut State University.  One year, full-time
non-tenure track position for Academic Year 1996-1997 to teach
discrete mathematics for CS students, theory of computation,
introductory and remedial mathematics courses.  Teaching excellence
and master's degree in mathematics required; doctorate preferred.
Review of applications begin August 8, 1996.  Send letter of
application, resume, transcript copies and three letters  of
recommendation to Dr. E. Sandifer, Mathematics and Computer Science
Department, WCSU, 181 White St., Danbury, CT 06810.  Western is an
Affirmative Action Equal Opportunity Educator/Employer

-----------------------------------------------------


Date:           Fri, 30 Aug 1996 08:05:52 -0400
To:             kcollins(at-sign)mail.wesleyan.edu
From:           kcollins(at-sign)wesleyan.edu (Karen L. Collins)
Subject:        First fall CoNE meeting


               Come to the Twenty-first one day conference on

Combinatorics and Graph Theory

Saturday, September 28, 1996

10 a.m. to 4:30 p.m.
at
Smith College
Northampton MA 01063

Schedule

10:00  Lixin Gao (Smith College)
Balancing Computational Load on Rings of Processors

11:10  Sorin Istrail (Sandia National Laboratories
and University of New Mexico)
Protein Folding: Combinatorial Problems and Algorithms

12:30  Lunch

2:00  Robin Pemantle (University of Wisconsin at Madison)
Recursions Coming in from Infinity on a Tree,
Applied to Models of Information Propagation

3:10  Clara Chan (Wesleyan University)
Counting Faces of Cubical Spheres Modulo 2

Our NSF grant to support these conferences has been renewed!
This will allow us to provide a modest transportation allowance
to those attendees who are not local.

Our Web page site has directions to Smith College, abstracts of
speakers, dates of future conferences, and other information.

Michael Albertson (Smith College), (413) 585-3865,
albertson(at-sign)smith.smith.edu

Karen Collins (Wesleyan Univ.), (860) 685-2169,
kcollins(at-sign)wesleyan.edu

Ruth Haas (Smith College), (413) 585-3872,
rhaas(at-sign)smith.smith.edu

From sara(at-sign)math.mit.edu Thu Sep 19 22:52:07 1996
To: combinatorics(at-sign)math.mit.edu
Subject: tomorrow

Combinatorics seminar for tomorrow, Friday September 1996:

"The Proof of a Conjecture of Zeilberger and Noonan".
Miklos Bona

Abstract:

Recently, attention has been paid to the problem of counting the number
of permutations of length $n$ containing a {\em given number $r$} (as
opposed to 0) of subsequences of a certain type $q$.
The main question  is to describe this function for {\em any
given $r$}, not just for $r=0$ or 1.  Zeilberger and
Noonan have conjectured that for {\em any} given subsequence $q$ and for {\em
any} given $r$,  the number
of $n$-permutations containing exactly $r$ subsequences of type $q$ is a
$P$-recursive function of $n$. To illustrate how far the solution of this
conjecture can be we note that if $q$ is longer than three, then we do
not have a proof even for $r=0$.

In this paper we solve this conjecture for the subsequence 132. This is
the first result we know of when the case of each $r$ is solved for some
given $q$. Some interesting consequences and special cases are included.
\end{document}

Upcoming events:

date:    Friday, September 27, 1996
speaker: Brian Taylor
title:   "A quadratic straightening law for row-convex tableaux."

date:    Friday October 4, 1996
speaker: Christian Lenart
title: Necklace Algebras and Witt Vectors Associated with Formal Group Laws.

From goemans(at-sign)math.mit.edu Mon Sep 23 10:04:13 1996
X-Sender: goemans(at-sign)severi
To: combinatorics(at-sign)math.mit.edu
Subject: Paul Erdos
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII

----- Begin Included Message -----

>From Diestel(at-sign)Mathematik.TU-Chemnitz.DE Sat Sep 21 20:30:07 1996

Message from Miklos Simonovits

Paul Erdos died Friday afternoon (20 September, 1996), in Warsaw.  Early
morning he felt some health problems, in a hotel in Warsaw.  So he was
carried into a hospital, where he died in the afternoon.  (He was 83).

=====================================

As far as I know, he had a heart attack, rather serious, very early in
the morning, in this Warsaw hotel, where he stayed while visiting the
Minisemester for Combinatorics, (for two weeks), gave two lectures.
Vera Sos and Andras Sarkozy are leaving Budapest for Warsaw right now,
Saturday morning, and Paul's original plans were to fly from Warsaw to
Vilnius (for the Kubilius Conference) with Vera and Andras together,
on Sunday.

The doctor informed us that he had two heart attacks and the second one
killed him. (Perhaps even the first one was serious enough to prevent
him from communicating to his surrounding.  This may explain e.g.
that he could not reach the mathematicians.  We learned about his
heart attacks only after his death.)

Miki Simonovits.

----- End Included Message -----

From schulte(at-sign)neu.edu Mon Sep 23 11:19:33 1996
X-Sender: schulte(at-sign)nuhub.dac.neu.edu (Unverified)
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
To: combinatorics(at-sign)math.mit.edu
Subject: seminar

NORTHEASTERN COMBINATORICS SEMINAR  --  Fall 1996
_________________________________________________

Northeastern's Combinatorics Seminar is back again (after a
"sabbatical year")!

The seminar meets Wednesdays at 1:30 - 2:30 pm in 509 Lake Hall.

September 25:   Alex Suciu,  Northeastern University

Combinatorics and topology of complex line
arrangements

October 2:      Alexander Postnikov, MIT

Deformations of Coxeter Arrangements

From schulte(at-sign)neu.edu Mon Sep 23 13:22:49 1996
X-Sender: schulte(at-sign)nuhub.dac.neu.edu (Unverified)
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
To: combinatorics(at-sign)math.mit.edu
Subject: NU seminar

NORTHEASTERN COMBINATORICS SEMINAR  --  Fall 1996
_________________________________________________

Usually the seminar meets Wednesdays at 1:30 - 2:30 pm in 509 Lake Hall.

September 25:   Alex Suciu,  Northeastern University

Combinatorics and topology of complex line
arrangements

October 2:      Alexander Postnikov, MIT

Deformations of Coxeter arrangements

Extra seminar on Friday October 11 at 1pm in 544 Nightingale Hall:

Eric Mendelsohn, University of Toronto

Intercalates (and Other Partial Latin Squares in 4 Cells)
Everywhere

November 6:     Peter Hamburger,  Indiana-Purdue University

Venn said it couldn't be done --
Planar graphs, Hamiltonian cycles and special families of
simple Jordan curves

From schulte(at-sign)neu.edu Thu Sep 26 17:36:23 1996
X-Sender: schulte(at-sign)nuhub.dac.neu.edu (Unverified)
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
To: combinatorics(at-sign)math.mit.edu
Subject: seminar

NORTHEASTERN COMBINATORICS SEMINAR  --  Fall 1996
_________________________________________________

Usually the seminar meets Wednesdays at 1:30 - 2:30 pm in 509 Lake Hall.

October 2:      Alexander Postnikov, MIT

Deformations of Coxeter arrangements

Extra seminar on Friday October 11 at 1pm in 544 Nightingale Hall:

Erik Mendelsohn, University of Toronto

Intercalates (and Other Partial Latin Squares in 4 Cells)
Everywhere

October 30:     Ludwig Danzer, University of Dortmund

SCD, a space-filler of 3-space with some surprising
properties

November 6:     Peter Hamburger,  Indiana-Purdue University

Venn said it couldn't be done --
Planar graphs, Hamiltonian cycles and special families of
simple Jordan curves

From sara(at-sign)math.mit.edu Fri Sep 27 11:12:34 1996
To: combinatorics(at-sign)math.mit.edu
Subject: today

**** Combinatorics Seminar 4:15pm Today****

Brian Taylor from M.I.T. will speak on "A quadratic straightening law
for row-convex tableaux."  See the abstract below OR chech out our new
Combinatorics Web Page designed by Maurice Rojas at
http://www-math.mit.edu/~rojas/Combinatorics/combi.html or you can get
to it by just going to "www-math.mit.edu" and clicking on "seminars".

A Quadratic Straightening Law for Row-Convex Tableaux

Brian Taylor, MIT

Just as (semi)standard Young tableaux index a basis for the irreducible
representations of $S_n$ (or $GL_n$) associated to the diagram of a
partition, one can ask for bases of the representations associated to more
general shapes. Considerable progress has been made, notably by Magyar and
by Reiner and Shimozono towards finding bases and character formulas for
the representations associated to a generalized shape. Most of these
results rely on either the Schensted algorithm or on jeu-de-taquin.

In the case of row-convex shapes, i.e. shapes like
{\obeyspaces\obeylines\global\let =\ \tt

xxxxxxxxxxxxx
xxxxxxxxxxxxx
xxxxxxxxxx
xxxxxxxxxxxxxx
xxxxxxxx
xx
xxxxxxx                                  }\par\noindent
which have no gaps in any row, it is possible to tell if a tableau
indexes a basis element by an easy combinatorial criterion involving
only pairs of rows. Further, for any pair of rows not fitting the
criterion, there exists a simple straightening law'' that replaces the
original pair of rows by a linear combination of better'' two-rowed
tableaux. Repeated applications of this straightening law expand any
tableau into a linear combination of basis elements.

The row-convex straightening law is characteristic-free and generalizes to
supertableaux and to quantum tableaux.

The representations used here are constructed, following Deruyts, as
subspaces (of a polynomial ring) which are spanned by products of
certain minors of a generic matrix. In keeping with the elementary nature
of the underlying construction, {\it this talk should be accessible to
non-specialists.}

Up coming events:

October 4: Christian Lenart
Necklace Algebras and Witt Vectors Associated with Formal Group Laws

October 11: Sara Billey
Kostant polynomials; interpolating polynomials for Schubert Polynomials

October 18: NO LECTURE (due to Posets Workshop at MSRI)

October 25: J. Maurice Rojas
Multisymmetric Functions via Toric Resultants

October 30 (Wednesday!): Gian-Carlo Rota
The Work of K. T. Chen (part I of II)

From IARROBIN(at-sign)neu.edu Mon Sep 30 13:34:40 1996
Subject: Combinatorics topic at NU GAS Oct 7
To: combinatorics(at-sign)math.mit.edu
X-Envelope-to: combinatorics(at-sign)math.mit.edu
X-VMS-To: IN%"combinatorics(at-sign)math.mit.edu"
MIME-version: 1.0
Content-transfer-encoding: 7BIT

Announcement:
Andrei Zelevinsky of Northeastern will speak on

"Total positivity in Schubert varieties"

in the GAS Seminar, Monday Oct 7 at noon, 509 Lake Hall, Northeastern.

A.I.


Date:           Tue, 1 Oct 1996 14:26:35 -0500
To:             combinatorics(at-sign)math.mit.edu
From:           schulte(at-sign)neu.edu (SCHULTE)
Subject:        seminar


          NORTHEASTERN COMBINATORICS SEMINAR  --  Fall 1996
_________________________________________________

Usually the seminar meets Wednesdays at 1:30 - 2:30 pm in 509 Lake Hall.

October 2:      Alexander Postnikov, MIT

Deformations of Coxeter arrangements

Extra seminar on Friday October 11 at 1pm in 544 Nightingale Hall:

Erik Mendelsohn, University of Toronto

Intercalates (and Other Partial Latin Squares in 4 Cells)
Everywhere

October 23:     Igor Pak, Harvard University

Partition identities, bijections and Groebner bases

October 30:     Ludwig Danzer, University of Dortmund

SCD, a space-filler of 3-space with some surprising
properties

November 6:     Peter Hamburger,  Indiana-Purdue University

Venn said it couldn't be done --
Planar graphs, Hamiltonian cycles and special families of
simple Jordan curves

November 13:    Alan Hoffman, IBM T.J. Watson Research Center

Greedy Algorithms in Linear Programming


Date:           Tue, 1 Oct 1996 14:53:33 -0400 (EDT)
From:           Jim Propp <propp(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        seminar archive and web-page


We have been having trouble with automatic archiving of messages sent to
combinatorics(at-sign)math.mit.edu; until it's fixed, messages will not automatically
be appended to http://www-math.mit.edu/~propp/combinatorics-archive/96b.
Sorry for any inconvenience.  In the meantime, you can keep up with what's
happening through Maurice Rojas' combinatorics seminar web page:
http://www-math.mit.edu/~rojas/Combinatorics/combi.html

Jim Propp


Date:           Wed, 2 Oct 1996 17:29:05 -0400 (EDT)
From:           Jim Propp <propp(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        Re: seminar archive and web-page


The archive is working once again.  You can access it via
http://www-math.mit.edu/~propp/combinatorics-archive/96b

Jim Propp


Date:           Thu, 3 Oct 1996 12:04:12 -0400 (EDT)
From:           Sara Billey <sara(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        seminar tomorrow


            ****Combinatorics Seminar Tomorrow ****

Necklace Algebras and Witt Vectors Associated with Formal Group Laws

Christian Lenart (M.I.T.)

Abstract:

We define and study a generalization of the {\em necklace algebra}
defined by N. Metropolis and G.-C. Rota [{\em Adv. Math}, {\bf 50},
1983, 95--125]; the generalized necklace algebra is associated with an
arbitrary formal group law $F(X,Y)$ over a torsion free ring $A$. The
map from the ring of Witt vectors associated with $F(X,Y)$ to the
necklace algebra is constructed in terms of certain generalizations of
the necklace polynomials. The actions of the {\em Verschiebung} and {\em
Frobenius} operators, as well as of the {\em p-typification idempotent},
are described and interpreted combinatorially. A formal group-theoretic
generalization of the {\em cyclotomic identity} is also presented. In
general, the necklace algebra can only be defined over the
rationalization of $A$, that is $A\otimes{\mathbb Q}$. Nevertheless, we
show that for an important family of formal group laws over the
integers, namely $F(X,Y)=(X+Y-(1+q)XY)/(1-qXY)$ with integer $q$, the
corresponding necklace algebra can be defined over the integers.
Furthermore, the generalized necklace polynomials turn out to be {\em
integral polynomials} in the variables $x$ and $q$, and they can be
interpreted combinatorially when $q$ is a prime power. We have thus
defined a $q$-deformation of the necklace algebra of Metropolis and
Rota. Our results imply the existence of nice ring structures on the
group of Witt vectors and the group of curves associated with the formal
group law parametrized by $q$.

Upcoming events:

date:    Friday October 11, 1996
speaker: Sara Billey
title:   Kostant polynomials; interpolating polynomials for Schubert Polynomials

date:    Friday October 18, 1996
NO COMBINATORICS SEMINAR DUE TO "POSETS" WORKSHOP AT MSRI


Date:           Mon, 7 Oct 1996 14:16:14 -0400
To:             kcollins(at-sign)mail.wesleyan.edu
From:           kcollins(at-sign)wesleyan.edu (Karen L. Collins)
Subject:        Oct. 26


               Come to the Twenty-second one day conference on

Combinatorics and Graph Theory

Saturday, October 26, 1996

10 a.m. to 4:30 p.m.
at
Smith College
Northampton MA 01063

Schedule

10:00  Bruce Kitchens (IBM)
Two Combinatorial Problems from Symbolic Dynamics

11:10  Joan Hutchinson (Macalester College)
Some 3- and 4-coloring theorem for the Plane, the
Projective Plane, and the Torus or Variations on
some themes of Heawood and Hadwiger

12:30  Lunch

2:00  Lenore Cowen (Johns Hopkins University)
Favorite Coloring Relaxations

3:10  Herman Servatius (WPI)
Doubly Periodic Self-dual Graphs and Tilings

Our NSF grant to support these conferences has been renewed!
This will allow us to provide a modest transportation allowance
to those attendees who are not local.  We gratefully acknowledge
support from Smith College and Wesleyan University as well.

Our Web page site has directions to Smith College, abstracts of
speakers, dates of future conferences, and other information.

Michael Albertson (Smith College), (413) 585-3865,
albertson(at-sign)smith.smith.edu

Karen Collins (Wesleyan Univ.), (860) 685-2169,
kcollins(at-sign)wesleyan.edu

Ruth Haas (Smith College), (413) 585-3872,
rhaas(at-sign)smith.smith.edu


Date:           Wed, 9 Oct 1996 12:15:07 -0500
To:             combinatorics(at-sign)math.mit.edu
From:           schulte(at-sign)neu.edu (SCHULTE)
Subject:        seminar


          NORTHEASTERN COMBINATORICS SEMINAR  --  Fall 1996
_________________________________________________

Extra seminar on Friday October 11 at 1pm in 544 Nightingale Hall:

Erik Mendelsohn, University of Toronto

Intercalates (and Other Partial Latin Squares in 4 Cells)
Everywhere

Usually the seminar meets Wednesdays at 1:30 - 2:30 pm in 509 Lake Hall.

October 23:     Igor Pak, Harvard University

Partition identities, bijections and Groebner bases

October 30:     Ludwig Danzer, University of Dortmund

SCD, a space-filler of 3-space with some surprising
properties

November 6:     Peter Hamburger,  Indiana-Purdue University

Venn said it couldn't be done --
Planar graphs, Hamiltonian cycles and special families of
simple Jordan curves

November 13:    Alan Hoffman, IBM T.J. Watson Research Center

Greedy Algorithms in Linear Programming


Date:           Wed, 9 Oct 1996 12:20:17 -0500
To:             combinatorics(at-sign)math.mit.edu
From:           schulte(at-sign)neu.edu (SCHULTE)
Subject:        Mendelsohn


          NORTHEASTERN COMBINATORICS SEMINAR  --  Fall 1996
_________________________________________________

Extra seminar on Friday October 11 at 1pm in 544 Nightingale Hall:

Eric Mendelsohn, University of Toronto

Intercalates (and Other Partial Latin Squares in 4 Cells)
Everywhere

\documentstyle{article}

\title{Intercalates (and Other Partial Latin Squares in 4 Cells) Everywhere}
\author{P. Danziger \\
Department of Mathematics \\
Ryerson University$^*$\\
\& \\
E. Mendelsohn \\
Department of Mathematics \\
University of Toronto
\thanks{The authors acknowledge
the support of NSERC (research grants \#OGP0170220 and \#OGP0077681 )}}

\date{}

\newtheorem{theorem}{Theorem}
\newtheorem{definition}{Definition}
\newtheorem{lemma}{Lemma}
\newtheorem{conjecture}{Conjecture}
\def\bt{\bibitem}

\begin{document}
\maketitle

\begin{center}
{\em This paper is dedicated to the memory of Peter Rodney Z{\tt "}L. (1965 -- 1
995)}
\end{center}

\begin{abstract}
The counting of the number of Intercalates, $2\times 2$
subsquares, possible in a latin Square of side $n$ is in
general a hard problem. $N_2$--Free latin squares, those for which there are
no intercalates, are known to exist for $n \neq 1,2,4$. $N_2$--complete
latin Squares, those which have the property that they have the maximum
number of $N_2$'s possible, $\frac{n}{2}\cdot {n\choose 2}$, must be isotopic
to $Z^k_2$ and thus of side $2^k$.  The maximum for $n\neq 2^k$ is in
general unknown.  We propose an intermediate possibility, that
of $N_2$--ubiquitous.  A latin Square is $N_2$ ubiquitous if and only if
every cell $a_{ij}$ is contained in some $2\times 2$ subsquare.  We
show these exist for $n\neq 1,3,5,7$.  It is also determined for which $n$.
$\cal C$--ubiquitous latin Squares exist for every partial latin Square,
$\cal C$ with four cells. We also enumerate the number of times each
4-cell configuration can appear in a latin square and show that this number
depends only on $n$ and the number of intercalates.
\end{abstract}
\end{document}


Date:           Thu, 10 Oct 1996 12:02:59 -0400 (EDT)
From:           Sara Billey <sara(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        seminar tomorrow


	****Combinatorics Seminar, Friday 4:15pm, 2-338 ****

Kostant polynomials; Interpolating Polynomials for Schubert Polynomials

Sara Billey (M.I.T.)

We will discuss the Kostant polynomials and their relationship to
Schubert polynomials and the Schubert calculus for $G/B$.  These
polynomials are defined by vanishing properties on the orbit of a
regular point under the action of the Weyl group.  For each element
$w$ in the Weyl group the polynomials also have non-zero values on the
orbit points corresponding to elements which are larger in the Bruhat
order than $w$.  Our main theorem is an explicit formula for these
values.  The matrix of orbit values can then be used to determine the
cup product for the cohomology ring for $G/B$, using only linear
algebra.  The main focus of the discussion will be for the case $W$ is
the symmetric group, however the results all hold for the Weyl group
of a Kac-Moody algebra.

Upcoming events:

date:    Friday October 18, 1996
NO COMBINATORICS SEMINAR DUE TO "POSETS" WORKSHOP AT MSRI

date:     October 25, 1996
speaker:  J. Maurice Rojas
title:    Multisymmetric Functions via Toric Resultants


From:           ALBERTSON(at-sign)smith.smith.edu
Date:           Tue, 15 Oct 1996 14:35:23 -0500 (EST)
Subject:        CoNE 10/26/96 inquiry
To:             joellis(at-sign)griffin.emba.uvm.edu, ssauyet(at-sign)claude.math.wesleyan.edu,
majors(at-sign)emmy.smith.edu, sheila(at-sign)claude.math.wesleyan.edu,
cchan(at-sign)claude.math.wesleyan.edu, dwylie(at-sign)claude.math.wesleyan.edu,
dlieb(at-sign)picasso.cslab.wesleyan.edu, gao(at-sign)grendel.csc.smith.edu,
goldston(at-sign)bard.edu, colbourn(at-sign)emba.uvm.edu, hurlbert(at-sign)cantor.la.asu.edu,
mduchin(at-sign)abel.math.harvard.edu, gsarkozy(at-sign)math.upenn.edu,
hoffa(at-sign)watson.ibm.com, wilf(at-sign)central.cis.upenn.edu, wilf(at-sign)math.upenn.edu,
calkin(at-sign)math.gatech.edu, loebl(at-sign)kam.ms.mff.cuni.cz,
whcunnin(at-sign)math.uwaterloo.ca, laura.hegerle(at-sign)dartmouth.edu,
michael.orrison(at-sign)dartmouth.edu, pcassidy(at-sign)smith.smith.edu,
lkrompar(at-sign)Oakland.edu, efa0(at-sign)lehigh.edu, rlg(at-sign)research.att.com,
pw(at-sign)research.att.com, shor(at-sign)research.att.com,
JEGCC%CUNYVM.BITNET(at-sign)eagle.wesleyan.edu, trenk(at-sign)dimacs.rutgers.edu,
LLESNIAK(at-sign)drew.edu, etesar(at-sign)drew.edu, klein(at-sign)sci.brooklyn.cuny.edu,
zamfi(at-sign)roz.hunter.cuny.edu, lvsnyder(at-sign)amherst.edu, bservat(at-sign)wpi.wpi.edu,
David.Mauro(at-sign)mail.cc.trincoll.edu, melanie.stein(at-sign)mail.cc.trincoll.edu,
chen(at-sign)math.umass.edu, ramesh(at-sign)oahu.cs.umass.edu, aab(at-sign)christa.unh.edu,
elcox(at-sign)conncoll.edu, epetrie(at-sign)emo.merrimack.edu,
carducci(at-sign)lafvax.lafayette.edu, pak(at-sign)abel.math.harvard.edu,
fomin(at-sign)math.mit.edu, sara(at-sign)math.mit.edu, cathan(at-sign)math.mit.edu,
apost(at-sign)math.mit.edu, lpachter(at-sign)math.mit.edu, dfinberg(at-sign)math.mit.edu,
bona(at-sign)math.mit.edu, djk(at-sign)math.mit.edu, ariki(at-sign)math.mit.edu,
mshimo(at-sign)math.mit.edu, satomi(at-sign)math.mit.edu,
beveridg(at-sign)pascal.math.yale.edu, JBONIN(at-sign)gwuvm.gwu.edu, rejam(at-sign)clemson.edu,
peterrc(at-sign)wpi.edu, lawsonn(at-sign)cs.rpi.edu, mathman(at-sign)brick.purchase.edu,
ftbbb(at-sign)cunyvm.bitnet, spaletaj(at-sign)wpi.wpi.edu,
elkies(at-sign)abel.math.harvard.edu, nate(at-sign)research.att.com,
moorthy(at-sign)cs.rpi.edu, streinu(at-sign)grendel.csc.smith.edu,
chung(at-sign)math.upenn.edu, jalfano(at-sign)eve.assumption.edu,
bkitchens(at-sign)MAIL.WESLEYAN.EDU, hochberg(at-sign)math.rutgers.edu,
jah(at-sign)christa.unh.edu, romanik(at-sign)dimacs.rutgers.edu,
lenhart(at-sign)cs.williams.edu, sheila(at-sign)paris-gw.cs.miami.edu, pavol(at-sign)cs.sfu.ca,
wantland(at-sign)mcs1.wcsu.ctstateu.edu, ross(at-sign)cs.amherst.edu,
kia(at-sign)oregano.unh.edu, simion%gwuvm.bitnet(at-sign)eagle.wesleyan.edu,
innes(at-sign)cs.uri.edu, finizio(at-sign)uriacc.uri.edu,
macula%geneseo.bitnet(at-sign)eagle.wesleyan.edu, kcirino(at-sign)lynx.dac.neu.edu,
propp(at-sign)math.mit.edu, rstan(at-sign)math.mit.edu, k.p.bogart(at-sign)dartmouth.edu,
sdc(at-sign)cs.albany.edu, peterrc(at-sign)wpi.wpi.edu, kcollins(at-sign)WESLEYAN.EDU,
rhaas(at-sign)smith.smith.edu, lrose(at-sign)sallie.WELLESLEY.EDU, jjr(at-sign)linus.mitre.org,
sandifer(at-sign)wcsub.ctstateu.edu, orourke(at-sign)sophia.smith.edu,
senechal(at-sign)minkowski.smith.edu, immerman(at-sign)freya.cs.umass.edu,
ccm(at-sign)cs.amherst.edu, diwan(at-sign)freya.cs.umass.edu,
grupen(at-sign)freya.cs.umass.edu, herbordt(at-sign)cs.umass.edu,
krithi%nirvan(at-sign)cs.umass.edu, lam(at-sign)cs.amherst.edu, liu(at-sign)freya.cs.umass.edu,
atrenk(at-sign)sallie.WELLESLEY.EDU, landau(at-sign)freya.cs.umass.edu,
malitz%oahu(at-sign)cs.umass.edu, rsnbrg(at-sign)freya.cs.umass.edu,
FRANZBLA(at-sign)dimacs.rutgers.edu, jhs(at-sign)math.cornell.edu,
kamck(at-sign)mvax.cc.conncoll.edu, albertson(at-sign)smith.smith.edu,
dbeers(at-sign)vmsvax.simmons.edu, bennett(at-sign)math.umass.edu,
fishel(at-sign)scsud.ctstateu.edu, gptesler(at-sign)euclid.ucsd.edu,
streinu(at-sign)sophia.smith.edu, eaton(at-sign)cs.uri.edu,
susan(at-sign)max.math.brandeis.edu, archdeac(at-sign)uvm-gen.emba.uvm.edu,
kenney(at-sign)siena.edu, hutchinson(at-sign)macalstr.edu,
plock%stlawu.bitnet(at-sign)eagle.wesleyan.edu, dvella(at-sign)skidmore.edu,
kwong(at-sign)mary.cs.fredonia.edu, lbutler(at-sign)acc.haverford.edu,
jsims(at-sign)eagle.wesleyan.edu, ecoven(at-sign)eagle.wesleyan.edu,
jlewis(at-sign)uriacc.uri.edu, sanjoy(at-sign)emba.uvm.edu, rjyanco(at-sign)unix.amherst.edu,
gara(at-sign)emba.uvm.edu, ravi(at-sign)cs.uri.edu, quintas(at-sign)pacevm.dac.pace.edu,
kennedyf(at-sign)pacevm.dac.pace.edu, lfeng(at-sign)eagle.wesleyan.edu,
ssilberger(at-sign)eagle.wesleyan.edu, bheiles(at-sign)eagle.wesleyan.edu,
silbergd%snynewvm.bitnet(at-sign)eagle.wesleyan.edu, discrete-math(at-sign)CS.YALE.EDU,
combinatorics(at-sign)math.mit.edu


We have received a request to alter the schedule of talks for the
October 26 meeting.  The revised schedule would have Servatius at 10,
Hutchinson at 11:10, Cowen at 2, and Kitchens at 3:10.  (Servatius and
Kitchens would trade places).  If you are planning to attend this
meeting and the proposed changes would have a negative impact upon you,

Combinatorially,

Mike Albertson


From:           ALBERTSON(at-sign)smith.smith.edu
Date:           Fri, 18 Oct 1996 13:20:28 -0500 (EST)
Subject:        CoNE 10/26/96
To:             joellis(at-sign)griffin.emba.uvm.edu, ssauyet(at-sign)claude.math.wesleyan.edu,
majors(at-sign)emmy.smith.edu, sheila(at-sign)claude.math.wesleyan.edu,
cchan(at-sign)claude.math.wesleyan.edu, dwylie(at-sign)claude.math.wesleyan.edu,
dlieb(at-sign)picasso.cslab.wesleyan.edu, gao(at-sign)grendel.csc.smith.edu,
goldston(at-sign)bard.edu, colbourn(at-sign)emba.uvm.edu, hurlbert(at-sign)cantor.la.asu.edu,
mduchin(at-sign)abel.math.harvard.edu, gsarkozy(at-sign)math.upenn.edu,
hoffa(at-sign)watson.ibm.com, wilf(at-sign)central.cis.upenn.edu, wilf(at-sign)math.upenn.edu,
calkin(at-sign)math.gatech.edu, loebl(at-sign)kam.ms.mff.cuni.cz,
whcunnin(at-sign)math.uwaterloo.ca, laura.hegerle(at-sign)dartmouth.edu,
michael.orrison(at-sign)dartmouth.edu, pcassidy(at-sign)smith.smith.edu,
lkrompar(at-sign)Oakland.edu, efa0(at-sign)lehigh.edu, rlg(at-sign)research.att.com,
pw(at-sign)research.att.com, shor(at-sign)research.att.com,
JEGCC%CUNYVM.BITNET(at-sign)eagle.wesleyan.edu, trenk(at-sign)dimacs.rutgers.edu,
LLESNIAK(at-sign)drew.edu, etesar(at-sign)drew.edu, klein(at-sign)sci.brooklyn.cuny.edu,
zamfi(at-sign)roz.hunter.cuny.edu, lvsnyder(at-sign)amherst.edu, bservat(at-sign)wpi.wpi.edu,
David.Mauro(at-sign)mail.cc.trincoll.edu, melanie.stein(at-sign)mail.cc.trincoll.edu,
chen(at-sign)math.umass.edu, ramesh(at-sign)oahu.cs.umass.edu, aab(at-sign)christa.unh.edu,
elcox(at-sign)conncoll.edu, epetrie(at-sign)emo.merrimack.edu,
carducci(at-sign)lafvax.lafayette.edu, pak(at-sign)abel.math.harvard.edu,
fomin(at-sign)math.mit.edu, sara(at-sign)math.mit.edu, cathan(at-sign)math.mit.edu,
apost(at-sign)math.mit.edu, lpachter(at-sign)math.mit.edu, dfinberg(at-sign)math.mit.edu,
bona(at-sign)math.mit.edu, djk(at-sign)math.mit.edu, ariki(at-sign)math.mit.edu,
mshimo(at-sign)math.mit.edu, satomi(at-sign)math.mit.edu,
beveridg(at-sign)pascal.math.yale.edu, JBONIN(at-sign)gwuvm.gwu.edu, rejam(at-sign)clemson.edu,
peterrc(at-sign)wpi.edu, lawsonn(at-sign)cs.rpi.edu, mathman(at-sign)brick.purchase.edu,
ftbbb(at-sign)cunyvm.bitnet, spaletaj(at-sign)wpi.wpi.edu,
elkies(at-sign)abel.math.harvard.edu, nate(at-sign)research.att.com,
moorthy(at-sign)cs.rpi.edu, streinu(at-sign)grendel.csc.smith.edu,
chung(at-sign)math.upenn.edu, jalfano(at-sign)eve.assumption.edu,
bkitchens(at-sign)MAIL.WESLEYAN.EDU, hochberg(at-sign)math.rutgers.edu,
jah(at-sign)christa.unh.edu, romanik(at-sign)dimacs.rutgers.edu,
lenhart(at-sign)cs.williams.edu, sheila(at-sign)paris-gw.cs.miami.edu, pavol(at-sign)cs.sfu.ca,
wantland(at-sign)mcs1.wcsu.ctstateu.edu, ross(at-sign)cs.amherst.edu,
kia(at-sign)oregano.unh.edu, simion%gwuvm.bitnet(at-sign)eagle.wesleyan.edu,
innes(at-sign)cs.uri.edu, finizio(at-sign)uriacc.uri.edu,
macula%geneseo.bitnet(at-sign)eagle.wesleyan.edu, kcirino(at-sign)lynx.dac.neu.edu,
propp(at-sign)math.mit.edu, rstan(at-sign)math.mit.edu, k.p.bogart(at-sign)dartmouth.edu,
sdc(at-sign)cs.albany.edu, peterrc(at-sign)wpi.wpi.edu, kcollins(at-sign)WESLEYAN.EDU,
rhaas(at-sign)smith.smith.edu, lrose(at-sign)sallie.WELLESLEY.EDU, jjr(at-sign)linus.mitre.org,
sandifer(at-sign)wcsub.ctstateu.edu, orourke(at-sign)sophia.smith.edu,
senechal(at-sign)minkowski.smith.edu, immerman(at-sign)freya.cs.umass.edu,
ccm(at-sign)cs.amherst.edu, diwan(at-sign)freya.cs.umass.edu,
grupen(at-sign)freya.cs.umass.edu, herbordt(at-sign)cs.umass.edu,
krithi%nirvan(at-sign)cs.umass.edu, lam(at-sign)cs.amherst.edu, liu(at-sign)freya.cs.umass.edu,
atrenk(at-sign)sallie.WELLESLEY.EDU, landau(at-sign)freya.cs.umass.edu,
malitz%oahu(at-sign)cs.umass.edu, rsnbrg(at-sign)freya.cs.umass.edu,
FRANZBLA(at-sign)dimacs.rutgers.edu, jhs(at-sign)math.cornell.edu,
kamck(at-sign)mvax.cc.conncoll.edu, albertson(at-sign)smith.smith.edu,
dbeers(at-sign)vmsvax.simmons.edu, bennett(at-sign)math.umass.edu,
fishel(at-sign)scsud.ctstateu.edu, gptesler(at-sign)euclid.ucsd.edu,
streinu(at-sign)sophia.smith.edu, eaton(at-sign)cs.uri.edu,
susan(at-sign)max.math.brandeis.edu, archdeac(at-sign)uvm-gen.emba.uvm.edu,
kenney(at-sign)siena.edu, hutchinson(at-sign)macalstr.edu,
plock%stlawu.bitnet(at-sign)eagle.wesleyan.edu, dvella(at-sign)skidmore.edu,
kwong(at-sign)mary.cs.fredonia.edu, lbutler(at-sign)acc.haverford.edu,
jsims(at-sign)eagle.wesleyan.edu, ecoven(at-sign)eagle.wesleyan.edu,
jlewis(at-sign)uriacc.uri.edu, sanjoy(at-sign)emba.uvm.edu, rjyanco(at-sign)unix.amherst.edu,
gara(at-sign)emba.uvm.edu, ravi(at-sign)cs.uri.edu, quintas(at-sign)pacevm.dac.pace.edu,
kennedyf(at-sign)pacevm.dac.pace.edu, lfeng(at-sign)eagle.wesleyan.edu,
ssilberger(at-sign)eagle.wesleyan.edu, bheiles(at-sign)eagle.wesleyan.edu,
silbergd%snynewvm.bitnet(at-sign)eagle.wesleyan.edu, discrete-math(at-sign)CS.YALE.EDU,
combinatorics(at-sign)math.mit.edu


The schedule for the October 26th meeting will be Servatius at 10,
Hutchinson at 11:10, Cowen at 2, and Kitchens at 3:10.  Refer to our

Mike Albertson


Date:           Mon, 21 Oct 1996 14:29:04 -0400
To:             kcollins(at-sign)mail.wesleyan.edu
From:           kcollins(at-sign)wesleyan.edu (Karen L. Collins)
Subject:        CoNE meeting


               **************Second Announcement**************
Come to the Twenty-second one day conference on

Combinatorics and Graph Theory

Saturday, October 26, 1996

10 a.m. to 4:30 p.m.
at
Smith College
Northampton MA 01063

Schedule

10:00  Herman Servatius (WPI)
Doubly Periodic Self-dual Graphs and Tilings

11:10  Joan Hutchinson (Macalester College)
Some 3- and 4-coloring theorem for the Plane, the
Projective Plane, and the Torus or Variations on
some themes of Heawood and Hadwiger

12:30  Lunch

2:00  Lenore Cowen (Johns Hopkins University)
Favorite Coloring Relaxations

3:10  Bruce Kitchens (IBM)
Two Combinatorial Problems from Symbolic Dynamics

Our NSF grant to support these conferences has been renewed!
This will allow us to provide a modest transportation allowance
to those attendees who are not local.  We gratefully acknowledge
support from Smith College and Wesleyan University as well.

Our Web page site has directions to Smith College, abstracts of
speakers, dates of future conferences, and other information.

Michael Albertson (Smith College), (413) 585-3865,
albertson(at-sign)smith.smith.edu

Karen Collins (Wesleyan Univ.), (860) 685-2169,
kcollins(at-sign)wesleyan.edu

Ruth Haas (Smith College), (413) 585-3872,
rhaas(at-sign)smith.smith.edu


Date:           Tue, 22 Oct 1996 12:25:45 -0500
To:             combinatorics(at-sign)math.mit.edu
From:           schulte(at-sign)neu.edu (SCHULTE)
Subject:        seminar


Usually the seminar meets Wednesdays at 1:30 - 2:30 pm in 509 Lake Hall.

October 23:     Igor Pak, Harvard University

Partition identities, bijections and Groebner bases

October 30:     Ludwig Danzer, University of Dortmund
(at 3:00pm)
SCD, a space-filler of 3-space with some surprising
properties

November 6:     Peter Hamburger,  Indiana-Purdue University

Venn said it couldn't be done --
Planar graphs, Hamiltonian cycles and special families of
simple Jordan curves

November 13:    Alan Hoffman, IBM T.J. Watson Research Center

Greedy Algorithms in Linear Programming


Date:           Tue, 22 Oct 1996 18:47:02 -0400 (EDT)
From:           Sara Billey <sara(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        pretalks


Starting with this Friday's Combinatorics seminar, we will initiate
pretalk discussions. These will take place (unless otherwise noted) in
2-338 from 3:30 to 4:00, and will be of a more casual nature. These
are primarily geared towards graduate students and others who want
more background before the official'' talk.

This Week!:

October 25: J. Maurice Rojas
Multisymmetric Functions via Toric Resultants


Date:           Sun, 27 Oct 1996 16:45:46 -0500 (EST)
From:           Sara Billey <sara(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        this week


This week we have two talks!  Prof. Rota will give a two part lecture
starting this Wednesday and continuing one week later.  There will be
no pretalk on Wednesday but I am trying to schedule one for Friday at
3:00.  This will be confirmed in a second message.  Upcoming events
are also below.

date:    Wednesday, October 30, 1996
speaker: Gian-Carlo Rota
title:   "The work of K.T. Chen"

date:    Friday, November 1, 1996
speaker: Arun Ram
title:   A proof, a generalization, and an application of a theorem
of Roichman

abstract: Recently, Y. Roichman gave a beautiful new formula for the
irreducible characters of the Iwahori-Hecke algebra (and for the
symmetic group and other Weyl groups).  In the type A case this
formula turns out to be equivalent to the Frobenius formula'' and,
indeed, looking at it this way yields a very simple proof of
Roichman's formula via the Robinson-Schensted-Knuth insertion scheme.
Armed with this simpler proof we can generalize Roichman's formula to
get new character formulas for Brauer and Birman-Wenzl algebras.
Finally, we shall apply this whole setup to compute the bitrace of the
regular representation of the Iwahori-Hecke algebra as a weighted sum
of matrices with nonnegative integer entries.

Upcoming events:

date:    Wednesday, November 6, 1996
speaker: Gian-Carlo Rota
title:   An Introduction to Baxter Operators

date:    Friday, November 8, 1996
speaker: Peter Hamburger
title:   Venn Said it Couldn't be Done:\\ Planar Graphs,
Hamiltonian Cycle, and Special Families of Simple Jordan Curve

date:    Friday, November 15, 1996
speaker: Huafei Yan
title:   Generalized Tree Inversions and $k$-Parking Function


Date:           Sun, 27 Oct 1996 21:51:57 -0500 (EST)
From:           G-C Rota <rota(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu, sara(at-sign)math.mit.edu
Subject:        Re:  this week


Perhaps I should give an inkling as to what the talk "The work of K.T. Chen" is
about.  As you know, a word in a free group with n generators can be represented
as a path in n-space. This representation has led to a number of conjectures and
theorems about words in free groups.
Chen's idea is to extend the notion of a free group so as to allow a generalized
word to be associated with any directed path in n space.  I will describe how this
is done, in the hope that someone will get interested in getting "continuous"
analogs of several known facts about words.
Gian-Carlo Rota.


Date:           Mon, 28 Oct 1996 15:55:07 -0500
To:             combinatorics(at-sign)math.mit.edu
From:           schulte(at-sign)neu.edu (SCHULTE)
Subject:        seminar


          NORTHEASTERN COMBINATORICS SEMINAR  --  Fall 1996
_________________________________________________

All talks are in 509 Lake Hall. The talk on October 30 is at 3:00pm.
All other talks are at 1:30pm.

October 30:     Ludwig Danzer, University of Dortmund
(at 3:00pm)
SCD, a space-filler of 3-space with some surprising
properties

November 6:     Peter Hamburger,  Indiana-Purdue University

Venn said it couldn't be done --
Planar graphs, Hamiltonian cycles and special families of
simple Jordan curves

November 13:    Alan Hoffman, IBM T.J. Watson Research Center

Greedy Algorithms in Linear Programming


Date:           Fri, 1 Nov 1996 13:05:59 -0500 (EST)
From:           Sara Billey <sara(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        seminar today


Today's seminar will be at 4:30pm instead of the usual 4:15 due to the
Faculty-Student get-together.  The Pretalk will be at 3:00 in 2-338.

****Combinatorics Seminar Today ****

A proof, a generalization, and an application
of a theorem of Roichman

Arun Ram (Princeton University)

Recently, Y. Roichman gave a beautiful new formula for the irreducible
characters of the Iwahori-Hecke algebra (and for the symmetric group
and other Weyl groups).  In the type A case this formula turns out to
be equivalent to the Frobenius formula'' and, indeed, looking at it
this way yields a very simple proof of Roichman's formula via the
Robinson-Schensted-Knuth insertion scheme.  Armed with this simpler
proof we can generalize Roichman's formula to get new character
formulas for Brauer and Birman-Wenzl algebras.  Finally, we shall
apply this whole setup to compute the bitrace of the regular
representation of the Iwahori-Hecke algebra as a weighted sum of
matrices with nonnegative integer entries.

Upcoming Events:

date:    Wednesday, November 6, 1996
speaker: Gian-Carlo Rota
title:   Continuation of "The work of K.T.Chen"

date:    Friday, November 8, 1996
speaker: Peter Hamburger
title:   Venn Said it Couldn't be Done:\\ Planar Graphs,
Hamiltonian Cycle, and Special Families of Simple Jordan Curve

date:    Friday, November 15, 1996
speaker: Huafei Yan
title:   Generalized Tree Inversions and $k$-Parking Function


Date:           Fri, 1 Nov 1996 19:10:57 -0500
To:             combinatorics(at-sign)math.mit.edu
From:           schulte(at-sign)neu.edu (SCHULTE)
Subject:        seminar


          NORTHEASTERN COMBINATORICS SEMINAR  --  Fall 1996
_________________________________________________

The seminar meets Wednesdays at 1:30 - 2:30 pm in 509 Lake Hall.

November 6:     Peter Hamburger,  Indiana-Purdue University

Venn said it couldn't be done --
Planar graphs, Hamiltonian cycles and special families of
simple Jordan curves

November 13:    Alan Hoffman, IBM T.J. Watson Research Center

Greedy Algorithms in Linear Programming


Date:           Fri, 1 Nov 1996 18:24:11 -0500 (EST)
From:           Sara Billey <sara(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        correction


My last message incorrectly stated the title of next week's talk.  The
correct title is as follows:

title:   An Introduction to Baxter Operators
speaker: Gian-Carlo Rota
date:    Wednesday, November 6, 1996

The coming talk will be independent from the talk this past Wednesday.


Date:           Thu, 7 Nov 1996 12:07:54 -0500 (EST)
From:           Lauren Rose <rose(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        Combinatorics Lunch - this Friday


We are starting a weekly combinatorics lunch at
the MIT faculty lunchroom, on the 2nd floor
of Walker Hall (above the cafeteria).

We will meet on Fridays from 12:00 - 1:00 pm,
starting TOMORROW.

All are welcome, but graduate students and
non-MIT faculty must be escorted by an MIT
faculty member.  Please meet at Sara Billey's
office (2-334) at 11:50am. and we will walk
over together.

The cost is only $3.00 and the food is pretty good!  Date: Fri, 8 Nov 1996 12:11:03 -0500 To: combinatorics(at-sign)math.mit.edu From: schulte(at-sign)neu.edu (SCHULTE) Subject: seminar   NORTHEASTERN COMBINATORICS SEMINAR -- Fall 1996 _________________________________________________ The seminar meets Wednesdays at 1:30 - 2:30 pm in 509 Lake Hall. November 13: Alan Hoffman, IBM T.J. Watson Research Center Greedy Algorithms in Linear Programming November 20: J. Maurice Rojas, MIT Counting Solutions of Sparse Polynomial Equation via Resultants  Date: Fri, 8 Nov 1996 11:13:29 -0500 (EST) From: Sara Billey <sara(at-sign)math.mit.edu> To: combinatorics(at-sign)math.mit.edu Subject: today   ****Combinatorics Seminar Today **** 4:15 in room 2-338, refreshments at 3:45 Speaker: Peter Hamburger (Indiana-Purdue University) Title: Venn Said it Couldn't be Done: Planar Graphs, Hamiltonian Cycle, and Special Families of Simple Jordan Curve Abstract: Using topological graph theory we will develop planar graph models to study the properties of special simple families of plane and spherical Jordan curves. Utilizing these procedures we solved some geometrical and topological problems. Among the others we answered some of the problems and conjectures of Professor Grunbaum. In this talk I will present some of our results on convex and strongly convex, simple, irreducible planar and spherical Venn diagrams. One of these results finally and fully corrects the erroneous statements that started with John Venn more than a century ago in 1880 and have been repeated frequently by others since then. We also will solve a conjecture of Grunbaum: Every Venn diagram on n curves can be extended to a Venn diagram of n+1 curves by the addition of a suitable simple closed Jordan curve. This finally solves a problem that goes back a century to John Venn's paper in 1880. We also will discuss a related conjecture of Peter Winkler. I will raise several problems and conjectures that arise from our work. I believe the talk will interest graph theorists and topologists as well as geometers, but it is accessible for any faculty or student with minimal knowledge of graph theory, topology, and geometry. Some of the results are joint results with Kiran B. Chilakamarri and/or Raymond E. Pippert (IPFW). } Upcoming events: date: Friday, November 15, 1996 speaker: Huafei Yan title: Generalized Tree Inversions and$k$-Parking Function date: Friday, November 22, 1996 speaker: Miller Maley title: "Hall Polynomials for Classical Groups"  Date: Wed, 13 Nov 1996 18:31:35 -0500 To: combinatorics(at-sign)math.mit.edu From: schulte(at-sign)neu.edu (SCHULTE) Subject: seminar   NORTHEASTERN COMBINATORICS SEMINAR -- Fall 1996 _________________________________________________ The seminar meets Wednesdays at 1:30 - 2:30 pm in 509 Lake Hall. November 20: J. Maurice Rojas, MIT Counting Solutions of Sparse Polynomial Equations via Resultants  Date: Wed, 13 Nov 1996 19:23:56 -0500 (EST) From: Lauren Rose <rose(at-sign)math.mit.edu> To: combinatorics(at-sign)math.mit.edu Subject: Combinatorics Lunch - this Friday  Come to the MIT faculty lunchroom on FRIDAY from 12-1 for the weekly combinatorics lunch. Get to know your colleagues! Last week we had a great turnout, including the speaker for that day. The lunchroom is on the 2nd floor of Walker Hall, and it's$3.00 for a buffet lunch.


Date:           Thu, 14 Nov 1996 13:34:39 -0500 (EST)
From:           Sara Billey <sara(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        seminar


            ****Combinatorics Seminar Tomorrow ****

Generalized Tree Inversions and $k$-Parking Function

Catherine Yan (M.I.T.)

Abstract:

Kreweras studied a polynomial $P_n(q)$ which enumerates (labeled)
rooted forests by number of inversions, as well as complements of
parking functions by the sum of their terms. Moreover, $P_n(1+q)$
enumerates labeled connected graphs by their number of excess
edges. For any positive integer $k$, there are known notions of
$k$-parking functions and of (labeled) rooted $k$-forests, generating
the case $k=1$ studied by Kreweras.  We show that the enumerator
$\overline{P}_n^{(k)}(q)$ for complements of $k$-parking functions by
the sum of their terms is identical to the enumerator of
$I_n^{(k)}(q)$ of rooted $k$-forests by the number of their
inversions.  In doing so we find recurrence relations satisfied by
$\overline{P}_n^{(k)}(q)$ and $I_n^{(k)}(q)$, and we introduce the
concept of a {\em multirooted $k$-graph} whose excess edges and roots
are enumerated by a polynomial denoted $C_n^{(k)}(q)$.  We show that
$C_n^{(k)}(q)$ satisfies the same recurrence relations as both
$\overline{P}_n^{(k)}(1+q)$ and $I_n^{(k)}(1+q)$, proving that
$\overline{P}_n^{(k)}(q) =I_n^{(k)}(q)$.

Upcoming Events:

date:    Friday, November 22, 1996
speaker: Miller Maley
title:   "Hall Polynomials for Classical Groups"
pretalk at 3:30pm for graduate students and non-experts in Hall polynomials.

date:    Friday, November 29, 1996
NO SEMINAR.  Happy Thanksgiving.


Date:           Sat, 16 Nov 1996 09:14:42 -0500
To:             kcollins(at-sign)mail.wesleyan.edu
From:           kcollins(at-sign)wesleyan.edu (Karen L. Collins)
Subject:        December 7


               Come to the Twenty-third one day conference on

Combinatorics and Graph Theory

Saturday, December 7, 1996

10 a.m. to 4:30 p.m.
at
Smith College
Northampton MA 01063

Schedule

10:00  Gary Gordon (Lafayette College)
Tutte Polynomials for Everyone

11:10  Noga Alon (Institute of Advanced Study, Tel Aviv Univ.)
Randomness and Pseudo-Randomness in Discrete Mathematics

12:30  Lunch

2:00  Norm Finizio (Univ. of Rhode Island)
Some Amazing Whist Tournament Designs

3:10  David Mauro (Trinity College)
Vertex Labelings with a Condition at Distance Two

Our NSF grant to support these conferences has been renewed!
This will allow us to provide a modest transportation allowance
to those attendees who are not local.  We gratefully acknowledge
support from Smith College and Wesleyan University as well.

Our Web page site has directions to Smith College, abstracts of
speakers, dates of future conferences, and other information.

Michael Albertson (Smith College), (413) 585-3865,
albertson(at-sign)smith.smith.edu

Karen Collins (Wesleyan University), (860) 685-2169,
kcollins(at-sign)wesleyan.edu

Ruth Haas (Smith College), (413) 585-3872,
rhaas(at-sign)smith.smith.edu


Date:           Fri, 22 Nov 1996 11:09:47 -0500 (EST)
From:           Sara Billey <sara(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        today


Miller Maley will be speaking today in the combinatorics seminar
starting at 4:15pm in 2-338 as usual.   The title of his talk will be
"Hall Polynomials for Classical Groups".  There will be a pretalk
starting at 3:30 in the same room for those who would like a more
elementary introduction.

Abstract:

Hall polynomials, which count invariant subspaces for a nilpotent
linear transformation acting on a vector space over a finite field,
are a key ingredient in the character theory of the group GL(n,q).  We
discuss the natural generalization of these polynomials to symplectic,
orthogonal, and unitary groups over the q-element field.  The speaker
has developed an efficient algorithm for computing these "Hall
functions", which makes it possible to discover and establish some of
their properties.  In particular, the algorithm shows that Hall
functions are polynomials in q with rational coefficients, and that
certain signed sums of these polynomials have integer coefficients.

Upcoming events:

date:    Wednesday, December 4, 1996 (tentative)
speaker:  Nantel Bergeron
title: Multiplication of Schubert Polynomials and Partial order

date:    Friday, December 6, 1996
speaker: Sheila Sundaram
title: The Whitehouse module in the homology of posets of partitions


Date:           Fri, 22 Nov 1996 13:52:11 -0500 (EST)
From:           Sara Billey <sara(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        correction


Correction to my last message.  Bergeron's talk is definite.

date:    Wednesday, December 4, 1996
speaker:  Nantel Bergeron
title: Multiplication of Schubert Polynomials and Partial order

Also, there won't be a talk on Nov. 29.  Happy Thanksgiving.


Date:           Fri, 22 Nov 1996 17:21:55 -0500 (EST)
From:           Jim Propp <propp(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        Combinatorial Commutative Algebra


                              First Announcement

Conference on  Combinatorial Commutative Algebra''

June 27. - 29. 1997

Universit\"at GH-Essen

Germany

General Topics & Program :

The conference is intended to promote the interaction between
Commutative Algebra and Combinatorics. Our plan is to gather
researchers that will provide expositions of classical and recent
developments on the borderline between Commutative Algebra &
Combinatorics.
Together with a second announcement, that will be posted in
December, we will mail out registration forms. In case there

Emanuela De Negri
Fachbereich 6, Mathematik
Universit\"at GH-Essen
45117 Essen
Germany
mat306(at-sign)uni-essen.de

List of speakers (preliminary, status November 22. 1996) :

Annetta Aramova (Bulgarian Academy of Sciences, Bulgaria)

J\"orgen Backelin (Stockholm Universitet, Sweden)

Takayuki Hibi (Osaka University, Japan)

Aldo Conca (Genova, Italy)

Ralf Fr\"oberg (Stockholm Universitet, Sweden)

Josef Gubelaze (A. Razmadze Mathematical Institute, Georgia)

Gil Kalai (Hebrew University, Jerusalem, Israel)

Clas L\"ofwall (Stockholm Universitet, Sweden)

Vic Reiner (University of Minnesota, USA)

Dorin Popescu (Bukarest, Rumania)

Emil Sk\"oldberg (Stockholm Universitet, Sweden)

Bernd Sturmfels (NOT CONFIRMED) (University of California, Berkeley, USA)

Program committee :

Winfried Bruns (Osnabr"uck)

J\"urgen Herzog (Essen)

Volkmar Welker (Essen)

G\"unter M. Ziegler (Berlin)

Participant support :

The conference is sponsored by the German Research Council DFG
through the Graduiertenkolleg Theoretische und experimentelle
Methoden in der reinen Mathematik'' and the Forschergruppe
Arithmetik und Geometrie.'' We can offer limited funds for
supporting some participants. Participants that would like to

Local Arrangements :

The conference will take place on the main campus of the University
of Essen located centrally in the city of Essen. Talks will start
in morning on Friday June 27 and the last talk will be given in the
late afternoon of June 29. We have made arrangements with several
hotels in Essen, so that we can offer reduced rates for conference
participants. A list of hotels will be provided together with the
second announcement.

Organizing committee :

Emanuela De Negri (Essen)

J\"urgen Herzog (Essen)

Volkmar Welker (Essen)


Date:           Wed, 27 Nov 1996 13:25:16 -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:        Combinatorics position (fwd)


Date:           Wed, 27 Nov 1996 12:15:07 -0500 (EST)
From:           KE Smith <kesmith(at-sign)math.lsa.umich.edu>


Date:           Wed, 27 Nov 1996 05:50:32 -0500 (EST)
From:           Alexandre Barvinok <barvinok(at-sign)math.lsa.umich.edu>


Below is the message I got from Victor Klee concerning possible
openings in combinatorics.
- -Sasha

- - - - - - -
For employment starting in September 1997, the University of
Washington Mathematics Department will have some open positions
--- two tenure-track assistant professorships and one non-tenure-
track acting assistant professorship. (Appointments at higher
levels are not excluded, but would be significantly more difficult
to arrange.) In connection with these appointments, the department
has several areas of priority, and Combinatorics is one of them.
Since the number of priority areas exceeds the number of available
positions, there is no guarantee that an appointment in
combinatorics will be made, but there is certainly some reason
to be hopeful in this connection. Thus I am writing to say that,
if you know of some especially promising young combinatorialists
who might be interested in moving to Seattle, I would appreciate
your informing them of this opportunity.

Applications should be sent to the following address:
Appointments Committee Chair, Department of Mathematics,
Box 354350, University of Washington, Seattle, WA 98195--4350.
A copy of the full announcement is appended below.

Within the Department of Mathematics, there are strong groups in
Discrete Geometry, in Optimization, and in parts of Graph Theory,
so candidates whose interests overlap with one or more of these
fields might be especially welcome. The same is true of those
with algorithmic interests, and there is a possibility of
interaction with the UW's strong Computer Science Department.
However, overall mathematical (and combinatorial) strength is of
greater importance than is any specific orientation within
combinatorics. Some breadth of research interests is also
desirable, as that would facilitate interaction with colleagues.

- - - - - - -
Here is the official announcement.

Applications are invited for several positions starting in
September, 1997. There is one three-year non-tenure track acting
assistant professorship available. There are also two positions
initially budgeted as tenure-track assistant professorships, but
sufficiently outstanding candidates may be considered at the
associate professor or professor level. Applicants must have the
Ph.D. degree in hand by the starting date. Duties include
Applications should include a curriculum vitae, statement of
research and teaching interests, three letters of recommendation,
and a Mathematics Subject Classification (as found in the
December index volumes of Mathematical Reviews) of their primary
research interest.

Applications should be sent to: Appointments Committee Chair,
Department of Mathematics, Box 354350, University of Washington,
Seattle, WA 98195--4350. Priority will be given to applications
received by December 15, 1996. The University of Washington is
building a culturally diverse faculty and strongly encourages
applications from female and minority candidates. The
University is an Equal Opportunity/Affirmative Action employer.
Availability of positions is subject to budgetary approval.
------- End of forwarded message -------


Date:           Mon, 2 Dec 1996 14:47:42 -0500 (EST)
From:           Lauren Rose <rose(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        Lecture: Monday Dec 2nd, 8pm


There is an interesting lecture tonight about polyhedra
sponsored by the Philomorph Society.  The meetings are
open to the general public.
*****************************************************

Dear Philomorphs,

"Virtual Reality Polyhedra"

George W. Hart
Dept. of Computer Science
Hofstra University

Monday, December 2nd, 1996 at 8:00 p.m.

Harvard University
Carpenter Center for the Visual Arts, Room 401
24 Quincy Street
Cambridge, Massachusetts

"Three-dimensional shapes can be described in standardized computer file
formats which may be seamlessly integrated with the internet and world-wide
web pages.  Author/artists can create three-dimensional objects which are
instantaneously viewable by interested readers around the world.  The viewer
can spin the objects on their screen (as real-time computer animations) or
move closer or further away, to gain different perspectives, just as one does
with a sculpture or physical three-dimensional model.  These virtual reality
models also have certain advantages over physical models:  one can travel
inside them; they can be physically disconnected; they can incorporate motion
and transformation.  I have been building a large collection of 3D polyhedron
models of this sort, many of which have never been constructed in paper.  I
will show examples and discuss some possibilities of these techniques.  A
preview is available at http://www.li.net/~george/virtual-polyhedra/vp.html"

The Philomorphs meet on the first Monday of each month during the Spring and
Fall semesters unless otherwise noted.  All meetings are free and open to the
public.  Interested friends and colleagues are welcome to attend.
Suggestions for future speakers or meeting topics, and notes on other items
of interest are encouraged.  Those wishing to receive future notices via
email may send a note to kthidemann(at-sign)aol.com.

All who receive this announcement by mail are asked to make a modest donation
to defray the reproduction and postage costs.  Many thanks to all who have
donated.  The 2-digit number next to your name on the address label is the
year through which you will remain on the active mailing list (i.e., '96
means you'll receive mailings at least through Dec. '96).  If no number
appears, you're on the list until further notice.  If you wish to be dropped
from the list at any time, please let us know that as well.  (Note: The
mailing list is continually in the process of being updated.  If you have
sent a renewal notice recently, the date listed next to your name on the
address label may not yet reflect this.)

Please make checks payable to "Philomorphs."

Philomorphs
Carpenter Center for the Visual Arts
Harvard University
Cambridge, MA 02138


Date:           Tue, 3 Dec 1996 13:58:32 -0500 (EST)
From:           Sara Billey <sara(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        seminar tomorrow


            ****Combinatorics Seminar Tomorrow ****
4:15pm in 2-334

Multiplication of Schubert Polynomials and Partial order

Nantel Bergeron (York University)

Abstract:

We introduce a partial order of the symmetric group related to the
multiplication of an arbitrary Schubert polynomial with a Schur
polynomial. Analogously to the weak Bruhat order and the nil-Coxeter
monoid, this order has an associated monoid M.
Finding a well behaved Knuth-cell decomposition of M would solve the
multiplication problem describe above.
The conjecture proposed by Winkel was promising,
but our study discovered a counter-example to it.

Upcoming events:

date:    Friday, December 6, 1996
speaker: Sheila Sundaram
title: The Whitehouse module in the homology of posets of partitions
abstract:
*****************
We present a class of  subposets of the partition
lattice $\Pi_n$ with the following property:
The order complex is homotopy equivalent to the order complex
of $\Pi_{n-1},$ and the $S_n$-module structure of the
homology coincides with
a recently discovered lifting of the $S_{n-1}$-action
on the homology of $\Pi_{n-1}.$
This is the Whitehouse representation on Robinson's space of
fully-grown  trees, and has since appeared in work of  Mathieu,
and Hanlon and Stanley.

One example is the subposet $P_n^{n-1}$ of the  lattice of set  partitions
$\Pi_n,$ obtained by removing all elements with a unique nontrivial block.
More generally, for $2\leq k\leq n-1,$
let $Q_n^k$ denote the subposet of the partition lattice
$\Pi_n$ obtained by removing all elements with a unique nontrivial block
of size  equal to $k,$ and let $P_n^k=\cap_{i=2}^k Q_n^i.$
We show that $P_n^k$ is Cohen-Macaulay with free integral homology,
and that $P_n^k$ and $Q_n^k$ are homotopy equivalent, with Betti number
$n!/k-(n-1)!.$  The posets $Q_n^k$ are neither shellable nor Cohen-Macaulay.
We give a simple formula for the homology as an $S_n$-module,
in terms of the homology modules of the partition
lattices $\Pi_k$ and $\Pi_n.$

***************
date:    Wednesday, December 11, 1996
Odessa University (Ukraine) and Ghent University (Belgium)
title:  Interaction between Combinatorics and Harmonic Analysis

We try to systematically employ observations that different
combinatorial notions (polynomial sequence of binomial
type, incidence coefficients, etc.) are generalization of
group characters. This allows to develop a new sort of
harmonic analysis rooted in combinatorics. Re-export of
abstractly elaborated tools to combinatorics widens
their scope of applications.


Date:           Tue, 3 Dec 1996 17:29:01 -0500 (EST)
From:           Sara Billey <sara(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        pretalk


There will be a pretalk tomorrow at 3:30pm before Nantel Bergeron's
talk.  Anyone interested in learning some background is welcome to
attend.


Date:           Fri, 6 Dec 1996 14:51:41 -0500 (EST)
From:           Sara Billey <sara(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        seminar today


            ****Combinatorics Seminar Today ****

The Whitehouse module in the homology of posets of partitions

Sheila Sundaram (Wesleyan University)

There is no pretalk today.

abstract:
*****************
We present a class of  subposets of the partition
lattice $\Pi_n$ with the following property:
The order complex is homotopy equivalent to the order complex
of $\Pi_{n-1},$ and the $S_n$-module structure of the
homology coincides with
a recently discovered lifting of the $S_{n-1}$-action
on the homology of $\Pi_{n-1}.$
This is the Whitehouse representation on Robinson's space of
fully-grown  trees, and has since appeared in work of  Mathieu,
and Hanlon and Stanley.

One example is the subposet $P_n^{n-1}$ of the  lattice of set  partitions
$\Pi_n,$ obtained by removing all elements with a unique nontrivial block.
More generally, for $2\leq k\leq n-1,$
let $Q_n^k$ denote the subposet of the partition lattice
$\Pi_n$ obtained by removing all elements with a unique nontrivial block
of size  equal to $k,$ and let $P_n^k=\cap_{i=2}^k Q_n^i.$
We show that $P_n^k$ is Cohen-Macaulay with free integral homology,
and that $P_n^k$ and $Q_n^k$ are homotopy equivalent, with Betti number
$n!/k-(n-1)!.$  The posets $Q_n^k$ are neither shellable nor Cohen-Macaulay.
We give a simple formula for the homology as an $S_n$-module,
in terms of the homology modules of the partition
lattices $\Pi_k$ and $\Pi_n.$

***************
date:    Wednesday, December 11, 1996
Odessa University (Ukraine) and Ghent University (Belgium)
title:  Interaction between Combinatorics and Harmonic Analysis

We try to systematically employ observations that different
combinatorial notions (polynomial sequence of binomial
type, incidence coefficients, etc.) are generalization of
group characters. This allows to develop a new sort of
harmonic analysis rooted in combinatorics. Re-export of
abstractly elaborated tools to combinatorics widens
their scope of applications.


Date:           Wed, 11 Dec 1996 13:06:48 -0500 (EST)
From:           Sara Billey <sara(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        today


This will be the last seminar for 1996.  Have a nice vacation.  See
you in February.

****Combinatorics Seminar Today ****
4:15pm in 2-338