From propp(at-sign)math.mit.edu Wed Sep 13 12:13:54 1995
To: combinatorics(at-sign)math.mit.edu
Subject: MIT Combinatorics Seminar: September schedule

		    MIT COMBINATORICS SEMINAR

Here is a list of talks currently scheduled for the month of September.
Notice that talks will normally begin at 4:35 p.m.

If you have an interest in presenting something short (as in last
semester's "combinatorial free-for-all"), let me know; if there's
enough interest, I will organize another free-for-all later in the
term.

Wednesday, September 20, 4:35 p.m.: Joseph Bonin,
	Matroids with no (q+2)-point-line minors

Friday, September 22, 4:35 p.m.: William Jockusch,
	Antisymmetric monotone triangles and domino tilings of quartered 
	Aztec diamonds

Friday, September 29, 4:35 p.m.: Karen Collins,
	Symmetry breaking in graphs

From propp(at-sign)math.mit.edu Wed Sep 13 12:44:27 1995
To: combinatorics(at-sign)math.mit.edu
Subject: Bonin, 9/20

Wednesday, September 20, 4:35 p.m.; MIT, room 2-338

		  Joseph Bonin (GWU and MIT)

           Matroids with no (q+2)-point-line minors
 

We are concerned with U(q), the class of matroids containing no minor 
isomorphic to the (q+2)-point line.  This class is of interest in part 
because of its connections with representability questions and its role
in extremal matroid theory, in particular, in connection with size functions.

For any prime power q, L(q) is a subset of U(q), where L(q) is the class 
of matroids representable over GF(q).  In 1958, Tutte proved that L(2) = 
U(2).  We will give a new proof of Tutte's theorem and sketch several 
other applications of the techniques used.

For prime powers q>2, the (q+2)-point line is not the only excluded minor
for GF(q)-representability.  However, we show that with enough points in 
a geometry, the (q+2)-point line is the only minor one must exclude to 
guarantee that the geometry is representable over GF(q).  Indeed, such 
geometries are uniquely representable over GF(q).  We will apply these 
ideas to bound the size function of U(q) and to obtain a simple counting 
characterization of affine space.

From propp(at-sign)math.mit.edu Fri Sep 15 08:36:37 1995
To: combinatorics(at-sign)math.mit.edu
Subject: MIT Combinatorics Seminar (October slots)

There are still some open slots for October; anyone wishing to speak on
October 18 or 27 should contact me as soon as possible.  (I will need a
title and abstract by the beginning of next week.)

Jim Propp

From propp(at-sign)math.mit.edu Tue Sep 19 23:46:09 1995
To: combinatorics(at-sign)math.mit.edu
Subject: Jockusch, 9/22

Friday, September 22, 4:35 p.m.; MIT, room 2-338

		     William Jockusch

	      Antisymmetric monotone triangles 
	and domino tilings of quartered Aztec diamonds

In earlier work it was shown that the Aztec diamond of order n has 
2^{n(n+1)/2} domino-tilings, and connections were established with 
monotone triangles and alternating sign matrices.  In this talk I will 
describe follow-up work that establishes formulas for the number of 
domino-tilings of a ``quarter'' of an Aztec diamond of order n, with 
different formulas depending on exactly how the quartering is done 
as well as on the residue of n mod 4.  

This turns out to be a special case of a more general enumeration problem,
where the number of domino-tilings of a certain kind of region is always 
equal to a power of 2 times the dimension of a particular representation
of a Lie algebra.  Our method of proof uses a weighted count of certain 
sorts of monotone triangles.  Interestingly, if one considers other 
enumeration problems for these monotone triangles, one gets conjectural 
product-formulas that generalize earlier conjectures of Mills, Robbins 
and Rumsey.

This is joint work with Jim Propp.

From propp(at-sign)math.mit.edu Wed Sep 20 20:14:04 1995
To: combinatorics(at-sign)math.mit.edu
Subject: Rota seminar

Gian-Carlo Rota's seminar on invariant theory, combinatorics, 
and supersymmetric algebra will have its first meeting on 
Friday, Sept. 22 at 6 p.m. in 2-338.

From propp(at-sign)math.mit.edu Fri Sep 22 12:10:00 1995
To: combinatorics(at-sign)math.mit.edu
Subject: Collins, 9/29

Friday, September 29, 4:35 p.m.; MIT, room 2-338

		  Karen Collins (Wesleyan)

		Symmetry breaking in graphs

A classic elementary problem with a surprise answer is the following:
if a circular key ring holds n identically shaped keys, and in order to
tell them apart, we plan to affix to each one a colored label, what is the
minimum number of different colors needed to distinguish the keys?  The 
surprise is that if n is at least 6, there need only be 2 different colors 
of labels; but if there are three, four, or five keys on the ring, there 
must be 3 different colors of labels.  If we consider the keys as vertices 
in the n-cycle, then the effect of the labels on the vertices is to destroy 
every symmetry of the n-cycle.

Define a labeling of a graph G,  l:V(G) --> {1,2,...,r}, to be 
_r-distinguishing_ if no automorphism of G preserves all of the vertex 
labels.  Then a natural question is, for any graph G, what is the minimum 
r such that G is r-distinguished?  For an n-cycle, the answer is 3 if
n=3,4,5 and 2 if n is at least 6.  For a complete graph on m vertices,
the answer is m.  We give a bound on the minimum distinguishing number 
of a graph in terms of the order of its automorphism group, as well as 
finding the distinguishing numbers of graphs whose automorphism groups 
are abelian, dihedral, S_3, or S_4.

This is joint work with Michael Albertson.

From propp(at-sign)math.mit.edu Fri Sep 22 18:55:50 1995
To: combinatorics(at-sign)math.mit.edu
Subject: MIT Combinatorics Seminar: October schedule

		    MIT COMBINATORICS SEMINAR

Here is a list of talks currently scheduled for the month of October.
Notice that talks scheduled on *Wednesdays* will normally begin at 
4:35 p.m., but that talks scheduled on Fridays will begin at *4:15*.

Wednesday, October 11, 4:35 p.m.: Joseph Bonin,
	A survey of Dowling lattices

Friday, October 13, 4:15 p.m.: Tal Kubo,
	Conway's recursive sequence

Wednesday, October 18, 4:35 p.m.: Thomas Sundquist,
	Pfaffians and theta functions

Friday, October 20, 4:15 p.m.: Ruth Haas,
	Decomposing graphs into trees

Wednesday, October 25, 4:35 p.m.: Kenneth Fan,
	Matchings and canonical forms for symmetric tensors 

Friday, October 27, 4:15 p.m.: Greg Kuperberg,
	Alternating-sign matrices and the Yang-Baxter equation

All talks will meet in room 2-338.

From propp(at-sign)math.mit.edu Fri Sep 22 20:33:52 1995
To: combinatorics(at-sign)math.mit.edu
Subject: AMS meeting at Northeastern

Participants in the MIT combinatorics seminar may be interested in attending 
the special session on ``Representation Theory and Combinatorics'' that will
be held at Northeastern University as part of the AMS regional meeting on 
October 7 and 8.  This special session will meet on Saturday, October 7 from 
8:30 to 10:50 a.m. and from 2:30 to 6:05 p.m., and on Sunday, October 8 from 
9:00 to 10:50 a.m. and from 2:30 to 5:35 p.m.

From propp(at-sign)math.mit.edu Fri Sep 22 20:44:10 1995
To: combinatorics(at-sign)math.mit.edu
Subject: more about AMS meeting

There will also be special sessions on 
	Graph Theory:
		Saturday, October 7, 8:30 a.m. to 10:50 a.m.
		Saturday, October 7, 2:30 p.m. to 5:50 p.m.
		Sunday, October 8, 8:30 a.m. to 10:50 a.m.
		Sunday, October 8, 2:30 p.m. to 5:50 p.m.
and
	Discrete Geometry 
		Saturday, October 7, 8:30 a.m. to 10:50 a.m.
		Saturday, October 7, 2:30 p.m. to 5:20 p.m.
		Sunday, October 8, 8:30 a.m. to 10:50 a.m.
(There may also be a Sunday afternoon session in Discrete Geometry,
for all I know; I only have partial information.)

From rstan(at-sign)math.mit.edu Fri Sep 22 20:54:48 1995
To: combinatorics(at-sign)math.mit.edu
Subject: AMS meeting at Northeastern II

Here is the tentative schedule of talks for the special session on
"Representation Theory and Combinatorics."

Saturday, October 7

 8:30 am   C. Kenneth Fan (Harvard University)
 9:00 am   Peter Magyar (University of Utrecht)
 9:30 am   Mark Shimozono (Massachusetts Institute of Technology)
10:00 am   Francesco Brenti (University of Perugia)
10:30 am   J. Matthew Douglass (University of North Texas)

 2:30 pm   Philip Hanlon (University of Michigan)
 3:00 pm   Daniel Rockmore (Dartmouth College)
 3:30 pm   David  Grabiner (Hebrew University)
 4:00 pm   Curtis Greene (Haverford College)

 4:45 pm   John Stembridge (University of Michigan)
 5:15 pm   Robert Proctor (University of North Carolina)
 5:45 pm   Adriano Garsia (University of California at San Diego)

Sunday, October 8

 8:30 am   Sheila Sundaram (University of Miami)
 9:00 am   Michelle Wachs (University of Miami)
 9:30 am   Victor Reiner (University of Minnesota)
10:00 am   William  Doran (California Institute of Technology)
10:30 am   Mark Haiman (University of California at San Diego)

 2:30 pm   Alexander Kirillov, Jr. (Yale University)
 3:00 pm   Pavel Etingof (Yale University)
 3:30 pm   Bernard Leclerc (University of Paris VII)

 4:15 pm   Toshiki Nakashima (University of Osaka)
 4:45 pm   Yan Soibelman (Kansas State University)
 5:15 pm   Eugene Stern (University of California at Berkeley)

From dynsys(at-sign)gibbs.oit.unc.edu Sat Sep 23 10:42:13 1995
Reply-To: bhasselb(at-sign)diamond.tufts.edu
Originator: dynsys(at-sign)gibbs.oit.unc.edu
Sender: dynsys(at-sign)gibbs.oit.unc.edu
To: Multiple recipients of list <dynsys(at-sign)gibbs.oit.unc.edu>
Subject: AMS meeting October 7-8
X-Listprocessor-Version: 6.0 -- ListProcessor by Anastasios Kotsikonas

		      Announcement of Special Sessions

	 American Mathematical Society Northeastern Section Meeting

	     Northeastern University, Boston, October 7-8, 1995

This  meeting has two sessions of  interest to dynamicists and all interested
colleagues are cordially invited to attend.

		      SPECIAL SESSION ON ERGODIC THEORY

Organizers: Stanley Eigen,	Eigen(at-sign)Northeastern.edu,	Northeastern University
	    V.S. Prasad,	PrasadV(at-sign)Woods.UML.edu,	UMass Lowell (& Tufts)

Current information   about this session  is  available from the organizers.
The schedule is as follows:

			Saturday Morning

8:30 -  8:50	Bruce Kitchens
			Dynamics of Markov groups
 9:00 -  9:20	Roy Adler
			Topological conjugacy of endomorphisms of 
			the 2-torus
 9:30 -  9:50	Jane Hawkins 
			Characterizing mildly mixing actions 
			using ratio sets and orbit equivalence.
10:00 - 10:20	Aimee S.A. Johnson 
			Loosely Bernoulli in $Z^d$
10:30 - 10:50	Cesar Silva
			Relatively weak mixing and infinite skew 
			product entropy

			Saturday Afternoon

 3:30 -  3:50	Adam Fieldsteel
			Dyadic equivalence to actions of completely 
			positive entropy
 4:00 -  4:20	Janet Whalen Kammeyer       
			Restricted Orbit Equivalence for 
			Actions of Discrete Amenable Groups
 4:30 -  4:50	Jonthan King       
			Interrelations between determinism, 
			zero-entropy and orbit separation
 5:00 -  5:20	Andres del Junco      
			Construction of simple measure-preserving 
			maps with prescribed automorphism group
 5:30 -  5:50	Nicholas S. Ormes
			Strong Orbit Realization for Minimal 
			Homeomorphisms

			Sunday Morning
 8:30 -  8:50	Robbie Robinson      
			Finite type property and topoloogical dynamics 
			for polyominoe tiling dynamical systems
 9:00 -  9:30	Boris Solomyak
			Ergodic theory of non-periodic tilings.
 9:30 -  9:50	Charles Radin
			Ergodic theory and the symmetry of tilings
10:00 - 10:20	James Propp
			A law of large numbers for the random 
			domino tiling process

			Sunday Afternoon
 2:30 -  2:50	Geoff Goodson
			$G$-Maps in the Centralizer of Compact 
			Abelian Group Extensions.
 3:00 -  3:20	B. S. Yadav     
			The Mean-Ergodic Theorem and Spectral 
			Decomposition of Complete isometries
 3:30 -  3:50	Gary L. Raduns, Jr.
			Comparison of Generalizations of the 
			Hopf Decomposition.

	    SPECIAL SESSION ON GEOMETRIC AND HYPERBOLIC DYNAMICS

Organizers: Zbigniew Nitecki,	ZNitecki(at-sign)Tufts.edu, Tufts University
	    Boris Hasselblatt,	BHasselb(at-sign)Tufts.edu, Tufts University

Current information about  this session  is available  on the  Worldwide  Web
under  the  URL  http://www.tufts.edu/~bhasselb/amsmtg.html,   and  from  the
organizers.

			     Saturday, October 7

 9:30	Juan Tolosa (Stockton College of New Jersey)
		Pattern families
10:00	Marco Martens (SUNY Stony Brook)
		Hyperbolicity of Circle Renormalization
10:30	Mark Levi (Rensselaer Polytechnic Institute)
		Deterministic randomness with positive probability

 2:40	Michael Shub (IBM)
		Stable Ergodicity and Partial Hyperbolicity (40 minutes)
 3:30	Slobodan Simic (UC Berkeley)
		Synchronization of Anosov flows
 4:00	Cymra Haskell (SUNY Stony Brook)
		The Infinite Periodic Lorentz Gas is Space-Time Bernoulli
 4:30	Amie Wilkinson (UC Berkeley)
		Stable ergodicity of maps arising from geodesic flows
 5:00	Fern Hunt (National Institute of Standards and Technology)
		Approximation of Attractors by Ulam's Method

			     Sunday, October 8:

 9:00	Ami Radunskaya
		KAM theory and the Fermi-Pasta-Ulam string model
 9:30	Tasso Kaper (Boston University)
		Hyperbolicity in near-integrable N degrees-of-freedom
		Hamiltonian systems
10:00	Pau Atela (Smith College)
		A remarkable global bifurcation diagram in a Hamiltonian system
10:30	Dmitri Kleinbock (Yale University)
		Nondense orbits of flows on homogeneous spaces

 2:30	Andrei Torok and Viorel Nitica (Princeton U. & Indiana U. Bloomington)
		Regularity of solutions for cocycle equations
 3:00	Alexei Kononenko (Pennsylvania State University)
		Cohomologies of group actions and their applications
 3:30	Nantian Qian (Yale University)
		Smooth conjugacy for Anosov diffeomorphisms and rigidity of
		Anosov actions of higher rank lattices
 4:00	Henk Bruin (Universitat Erlangen)
		Cantor-attractors for interval maps

Stan Eigen would like to invite all participants to the following event:

			   Ig Nobel Award Ceremony
			  October 6, 1995, 7:30 PM
		       Lowell Hall, Harvard University

(Tickets need to be bought in advance; contact info(at-sign)improb.com.)

From kcollins(at-sign)MAIL.WESLEYAN.EDU Mon Sep 25 11:41:38 1995
X-Sender: kcollins(at-sign)mail.wesleyan.edu
To: combinatorics(at-sign)math.mit.edu
MIME-version: 1.0
Content-type: text/plain; charset="us-ascii"
Content-transfer-encoding: 7BIT

Here is the tentative schedule of talks for the special session on
"Graph Theory."

Saturday, Oct. 7, 1995

8:30   Nancy Eaton, Univ. of Rhode Island
9:00   C. Zhang, W. Virginia University
9:30   Ruth Haas, Smith College
10:00  Claude Tardif, University of Montreal
10:30  Gena Hahn,  University of Montreal

2:30   Gara Pruesse, University of Vermont
3:00   Lenwood Heath, Virginia Polytech Inst. & State Univ.
3:30   Kathy McKeon, Conn. College

4:00  BREAK

4:30   Linda Lesniak, Drew University
5:00   Daniel Kleitman, MIT
5:30   Seth Chaiken, SUNY Albany

Sunday, Oct. 8, 1995

8:30   Lauren Rose, Wellesley College
9:00   Brigitte Servatius, WPI
9:30   Herman Servatius, MIT
10:00  Karen Collins, Wesleyan Univ.
10:30  Michael Albertson, Smith College

2:30   Ann Trenk, Wellesley College
3:00   Ken Bogart, Dartmouth College
3:30   Ross McConnell, Amherst College

4:00 BREAK

4:30   Dave Berman, Univ. of New Orleans
5:00   Emily Petrie, Arizona State Univ.
5:30   Kathleen Romanik, DIMACS

---------------------------
Department of Mathematics
Wesleyan University
Middletown CT 06459-0128
Fax:  (860) 685-2571
---------------------------

From propp(at-sign)math.mit.edu Tue Oct  3 00:00:19 1995
To: combinatorics(at-sign)math.mit.edu
Subject: Bonin, 10/11

Wednesday, October 11, 4:35 p.m.; MIT, room 2-338

	Joseph Bonin (George Washington University and MIT):

		   A survey of Dowling lattices

Dowling lattices arose in connection with the theory of linear codes and as
q-analogs of partition lattices, and they were quickly seen to be of use
for studying arrangements of hyperplanes.  These geometric lattices also
provided the motivation for biased graphs, and, like projective spaces and
free matroids, they are the universal models for one of the five types of
varieties of combinatorial geometries.  This talk will provide an introduction
to these lattices and will outline several recent advances in the theory.

The first class of results to be treated brings out similarities between
Dowling lattices and projective spaces.  This includes an axiom scheme for
Dowling lattices, analogs of Desargues' and Pappus' theorems, and a
coordinatization theory analogous to that for projective spaces.  We will
also present an application of the automorphism theory for Dowling lattices.

The second collection of results to be discussed involves the Tutte
polynomial, the matroid counterpart of the dichromatic polynomial of graph
theory.  The Tutte polynomial of any matroid contains much information about
the matroid, and this is especially true for Dowling lattices.  We will
explore exactly how much information about a Dowling lattice is reflected in
its Tutte polynomial.

From propp(at-sign)math.mit.edu Tue Oct  3 00:00:24 1995
To: combinatorics(at-sign)math.mit.edu
Subject: Kubo, 10/13

Friday, October 13, 4:15 p.m.; MIT, room 2-338

			Tal Kubo (Harvard)

		    Conway's recursive sequence
 

Sequences obeying  a(n) = a(a(n-1))+a(n-a(n-1))  have been explored by
Conway, Hofstadter, Mallows, Kleitman and others.  They have beautiful and
intricate properties: combinatorial (symmetry, self-similarity), analytic
(asymptotics related to the Gaussian distribution), and arithmetic (e.g.,
a(2^n)=2^{n-1}).  We will show that a(n) can be viewed not as a
complicated sequence, but as a simple compression operation on finite sets.
Combinatorial structures including trees, Fibonacci and Catalan numbers,
refinements of Pascal's triangle, and a mysterious appearance of Nim-like
games, are encountered on the way.  (These results were obtained in
collaboration with R. Vakil.)

Date:           Thu, 5 Oct 1995 12:08:12 -0400
From:           Jim Propp <propp(at-sign)math.mit.edu>
To:             tiling(at-sign)math.mit.edu
Subject:        Electronic Classroom

If latecomers to the UROP today find that 2-255 is empty, come look for
us in 14-0637.  (It's in the basement of the building that contains the
Science Library.)

Jim

Date:           Fri, 6 Oct 1995 10:21:36 -0400 (EDT)
From:           Satomi Okazaki <satomi(at-sign)math.mit.edu>
To:             noetherian(at-sign)schauder.mit.edu, combinatorics(at-sign)schauder.mit.edu
Subject:        Reminder - Today at 5pm - Noetherian Ring seminar

                         The NOETHERIAN RING at MIT

                           would like to announce 
             biweekly half-hour talks given by women in mathematics
            followed by a half-hour for socializing and refreshments.

    The talks are meant to be accessible to a general mathematical audience.

                            Everyone is welcome.

                             Friday, October 6

                         5:00pm in room 2-136, MIT
                         (please note room change)

                 Professor Lynne M. Butler, Haverford College

          "An example of the topological perspective in combinatorics"

   Many beautiful theorems in algebraic topology have analogues in the theory
   of partially ordered sets.  For example, Stanley discovered an Alexander
   duality theorem for Eulerian posets.  In this talk we show how an
   observation of Matveev's, on how to compute the M\"obius number of a
   poset from edge coverings of its incomparability graph, may be quickly
   deduced from Stanley's Alexander duality theorem.

Date:           Tue, 10 Oct 1995 18:09:27 -0400
From:           Jim Propp <propp(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        Sundquist, 10/18

Wednesday, October 18, 4:35 p.m.; MIT, room 2-338

		Thomas Sundquist (Dartmouth)

		Pfaffians and theta functions

The classical theory of Elliptic Functions gives rise to many interesting 
theta function identities such as
	P(b+e) P(b-e) P(c+d) P(c-d) - P(b+d) P(b-d) P(c+e) P(c-e)
		+ q^(c-d) P(b+c) P(b-c) P(d+e) P(d-e) = 0,
where P is a rescaled version of Jacobi's third theta function.  The proofs 
of these identities typically are analytic, or rely on invoking standard 
facts about the finite dimensional space of modular forms of a given weight.  
Other theta function identities, like Jacobi's Triple Product which factors 
a theta function into three infinite products, have nice combinatorial 
interpretations and proofs.  In this talk I will discuss a simple 
``symmetric function theory'' proof of a generalization of the former 
identity.  The technique involves expressing the combination of theta 
functions as the Pfaffian of a 4 by 4 skew-symmetric matrix, and then 
expanding the Pfaffian as a (vanishing) sum of alternants.  Finally,
we generalize the proof to give interesting expansions for Pfaffians of
other ``theta-like'' functions.

Date:           Tue, 10 Oct 1995 18:16:00 -0400
From:           Jim Propp <propp(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        Haas, 10/20

Friday, October 20, 4:15 p.m.; MIT, room 2-338

		      Ruth Haas (Smith)

		Decomposing graphs into trees
 

The original characterization for when a graph can be decomposed into 
k spanning forests was given by Nash-Williams in 1964.  In this talk 
we give several old and new characterizations for the following two 
classes of graphs:  (i) graphs for which adding _some_ m edges produces 
a graph which is decomposable into k spanning trees, i.e., the graph 
has arboricity k; and  (ii) graphs for which adding _any_  m edges 
produces a graph which is decomposable into k spanning trees.

The study of the second of these is motivated by some results in 
combinatorial rigidity. In particular, a graph is rigid in the plane 
if it can be "constructed" using rigid bars for the edges and rotatable 
joints for the vertices so that the only possible motions in the plane 
are translation and rotation.  Lovasz and Yemini showed that a graph is
minimally rigid in the plane (removal of any edge would make it not 
rigid) if and only if adding any edge to the graph, including a multiple 
edge results in a graph which is decomposable into 2 spanning trees. 
A recent paper of Crapo gives another characterization of this class 
and it is this characterization that we extend to other cases. 

Date:           Wed, 11 Oct 1995 18:18:50 -0400
From:           Jim Propp <propp(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        Discrete Dinner

It's getting to be time to plan this semester's DISCRETE DINNER.

If you have suggestions for a restaurant, please pass them on to me.

Meanwhile, I'd like people's comments on the following dates:

Wednesday, Nov. 1
Friday, Nov. 3
Wednesday, Nov. 8
Friday, Nov. 10
Wednesday, Nov. 15
Wednesday, Nov. 17

Jim

From:           RHAAS(at-sign)smith.smith.edu
Date:           Sun, 15 Oct 1995 11:32:34 -0500 (EST)
Subject:        November 11th meeting of the Combinatorists of  New England
To:             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, btesar(at-sign)mail.cog.jhu.edu,
                mloebl(at-sign)jeeves.uwaterloo.ca, JBONIN(at-sign)gwuvm.gwu.edu, rejam(at-sign)clemson.edu,
                peterrc(at-sign)wpi.edu, jziu(at-sign)maristb.marist.edu, lawsonn(at-sign)cs.rpi.edu,
                mathman(at-sign)brick.purchase.edu, ftbbb(at-sign)cunyvm.edu, spaletaj(at-sign)wpi.wpi.edu,
                atkins(at-sign)wpi.edu, elkies(at-sign)abel.math.harvard.edu, emann(at-sign)fas.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)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(at-sign)gwuvm.bitnet, innes(at-sign)cs.uri.edu,
                mcrystal(at-sign)bbn.com, finizio(at-sign)uriacc.uri.edu, macula(at-sign)geneseo.bitnet,
                kcirino(at-sign)lynx.dac.neu.edu, propp(at-sign)math.mit.edu, rstan(at-sign)math.mit.edu,
                combinatorics(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)eagle.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,
                girkar(at-sign)freya.cs.umass.edu, grupen(at-sign)freya.cs.umass.edu,
                guruvado(at-sign)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,
                lory(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, adean(at-sign)skidmore.edu, jzca(at-sign)marist.bitnet,
                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,
                llangley(at-sign)carbon.denver.colorado.edu, Tom.Sundquist(at-sign)dartmouth.edu,
                rajpal(at-sign)griggs.dartmouth.edu, dbeers(at-sign)vmsvax.simmons.edu,
                bennett(at-sign)math.umass.edu, fishel(at-sign)scsud.ctstateu.edu, lenore(at-sign)math.mit.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.bitnet, hutchinson(at-sign)macalstr.edu,
                lovasz-laszlo(at-sign)cs.yale.edu, plock(at-sign)stlawu.bitnet, 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,
                krg(at-sign)rover.wellesley.edu, Rhoades(at-sign)emmy.smith.edu, hull(at-sign)cs.uri.edu,
                rajpal(at-sign)dartmouth.edu, silbergd(at-sign)snynewvm.bitnet

               Come to the seventeenth one day conference on

                     Combinatorics and Graph Theory

                      Saturday, November 11, 1995

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

                               Schedule

10:00  Esther Tesar (Drew University)
        Some Extensions of the Genus Distribution of
         Closed-End Ladders

11:10   Laszlo Lovasz (Yale University)
	     The Matching Structure of Graphs

12:10  Lunch

 2:00  Joe Bonin (George Washington University)
        A Survey of Dowling Lattices

 3:10  Robert Jamison (Clemson University)
        Monotaxis in Matroids and Antimatroids

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

We have received an NSF grant to support these conferences. This
will allow us to provide a modest transportation allowance to those
attendees who are not local.

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

Karen Collins (Wesleyan Univ.), (203) 685-2169,
kcollins(at-sign)wesleyan.edu

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

Date:           Wed, 18 Oct 1995 14:04:29 -0400
From:           Jim Propp <propp(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        Web-access for past postings

A self-updating archive of postings to the combinatorics mailing list 
(combinatorics(at-sign)math.mit.edu) during the last several years is now 
available on the Web:

        http://www-math.mit.edu/~propp/combinatorics_archive/

(The old archive on theory.lcs.mit.edu has been discontinued.)

Jim Propp

From propp(at-sign)math.mit.edu Wed Oct 18 15:41:04 1995
To: combinatorics(at-sign)math.mit.edu
Subject: Fan, 10/25

Wednesday, October 25, 4:15 p.m.; MIT, room 2-338

			C. Kenneth Fan (MIT):

	Matchings and canonical forms for symmetric tensors
 

Let V be a q-dimensional vector space.  Fix a set B of q(q-1) monomials 
in S^p(V) of the form x^I where i_k>0 for all k.  The generic element of 
S^p(V) is conjugate under a suitable linear transformation to an element 
with support off of B.  We prove this by showing the existence of a perfect
matching with a unique weight in a certain weighted bipartite graph.  
Such a perfect matching corresponds to the non-vanishing of an appropriate 
determinant.

This is joint work with Jozsef Losonczy.

From propp(at-sign)math.mit.edu Wed Oct 18 15:47:15 1995
To: combinatorics(at-sign)math.mit.edu
Subject: Kuperberg, 10/27

Friday, October 27, 4:15 p.m.; MIT, room 2-338

			Greg Kuperberg (Yale)

	Alternating-sign matrices and the Yang-Baxter equation

Robbins conjectured, and Zeilberger recently proved, that there are

			 1!4!7!...(3n-2)!
			------------------
			n!(n+1)!...(2n-1)!

alternating sign matrices of order n.  We will discuss a new proof of 
this result using an analysis of the six-vertex state model (also called
square ice) based on the Yang-Baxter equation.

Date:           Tue, 24 Oct 1995 15:16:05 -0400 (EDT)
From:           Jim Propp <propp(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        Stanley, 11/3

Friday, November 3, 4:15 p.m.; MIT, room 2-338

			Richard Stanley (MIT)

	 Hyperplane arrangements, interval orders, and trees
 

Abstract: A (real) hyperplane arrangement is a finite set of affine
hyperplanes in R^n.  A central problem in the theory of hyperplane 
arrangements is to count the number of regions into which the 
hyperplanes subdivide R^n.  For instance, the number of regions of 
the arrangement (known as the _braid_arrangement_) consisting of all 
hyperplanes x_i = x_j, i<j, is easily seen to be n!.  We will consider 
some modifications (deformations) of the braid arrangement and show 
some surprising connections with such topics as interval orders and 
the enumeration of trees.  In particular, there is an explicit conjecture 
for the number of regions of the arrangement x_i - x_j=1, i<j.  Much 
of this work was done in collaboration with Nati Linial, Igor Pak, 
Alexander Postnikov, and Schmulik Ravid.

Date:           Tue, 24 Oct 1995 15:18:04 -0400 (EDT)
From:           Jim Propp <propp(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        DISCRETE DINNER

	Fall 1995 Boston Area Discrete Mathematics Dinner

This semester's Discrete Dinner will be held on Friday, November 3
at 6 p.m. at Thai's Restaurant (1 Kendall Square), just a few blocks 
from MIT.  The cost will be $7 for grad students and undergraduates
(not counting alcoholic beverages), with the rest of us making up the 
difference.  I hope that the closeness to campus and the low cost of 
the meal will encourage graduate students and undergraduates to attend.

Please let me know by October 31 (preferably electronically) your 
probability of attendance.  My e-mail address is propp(at-sign)math.mit.edu; 
if you don't have e-mail, call 253-6544.

Date:           Wed, 1 Nov 1995 15:36:59 -0500 (EST)
From:           Jim Propp <propp(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        MIT Combinatorics Seminar: November schedule

		    MIT COMBINATORICS SEMINAR

Here is a list of talks currently scheduled for the month of November.
Notice that talks scheduled on *Wednesdays* will begin at *4:35* p.m., 
but that talks scheduled on *Fridays* will begin at *4:15*.

Friday, November 3, 4:15 p.m.: Richard Stanley,
	Hyperplane arrangements, interval orders, and trees
	(followed by Discrete Dinner)

Wednesday, November 8, 4:35 p.m.: Ira Gessel,
	Counting binary trees by ascents and descents

Wednesday, November 15, 4:35 p.m.: Miklos Bona,
	Permutations avoiding certain patterns

Friday, November 17, 4:15 p.m.: David Jackson,
	The genus series for monopoles and the Euler characteristic 
	for the moduli spaces of real algebraic curves

Wednesday, November 29, 4:35 p.m.: Open mike (featuring Gian-Carlo 
	Rota, Dan Kleitman, Christos Athanasiadis, and others)

All talks will meet in room 2-338.

Date:           Wed, 1 Nov 1995 15:37:39 -0500 (EST)
From:           Jim Propp <propp(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        Gessel, 11/8

Wednesday, November 8, 4:35 p.m.; MIT, room 2-338

		    Ira Gessel (Brandeis)

	Counting binary trees by ascents and descents

The number of unlabeled binary trees on n vertices is the Catalan
number C_n={1 \over n+1}{2n \choose n}, so the number of labeled
binary trees is n! C_n. We call a vertex of a labeled binary tree
(with totally ordered vertices) a _left_ascent_ if it is a left
child and is greater than its parent, and we define right ascents 
and left and right descents similarly.

In this talk I will count labeled binary trees by left and right
ascents and descents. Special cases yield Eulerian numbers and the
number (n+1)^{n-1} of labeled rooted forests. There are also some
non-obvious symmetries: There is a symmetry that switches left ascents
with right descents, and by allowing repeated labels we obtain
symmetric functions which I conjecture to be Schur-positive.

From:           RHAAS(at-sign)smith.smith.edu
Date:           Wed, 08 Nov 1995 12:24:44 -0500 (EST)
Subject:        Schedule change for Saturday Nov 11 CONE meeting
To:             lvsnyder(at-sign)amherst.edu, zamfi(at-sign)roz.hunter.cuny.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, btesar(at-sign)mail.cog.jhu.edu,
                mloebl(at-sign)jeeves.uwaterloo.ca, JBONIN(at-sign)gwuvm.gwu.edu, rejam(at-sign)clemson.edu,
                peterrc(at-sign)wpi.edu, jziu(at-sign)maristb.marist.edu, lawsonn(at-sign)cs.rpi.edu,
                mathman(at-sign)brick.purchase.edu, ftbbb(at-sign)cunyvm.edu, spaletaj(at-sign)wpi.wpi.edu,
                elkies(at-sign)abel.math.harvard.edu, emann(at-sign)fas.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)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(at-sign)gwuvm.bitnet, innes(at-sign)cs.uri.edu,
                mcrystal(at-sign)bbn.com, finizio(at-sign)uriacc.uri.edu, macula(at-sign)geneseo.bitnet,
                kcirino(at-sign)lynx.dac.neu.edu, propp(at-sign)math.mit.edu, rstan(at-sign)math.mit.edu,
                combinatorics(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)eagle.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,
                girkar(at-sign)freya.cs.umass.edu, grupen(at-sign)freya.cs.umass.edu,
                guruvado(at-sign)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,
                lory(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, adean(at-sign)skidmore.edu, jzca(at-sign)marist.bitnet,
                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,
                llangley(at-sign)carbon.denver.colorado.edu, Tom.Sundquist(at-sign)dartmouth.edu,
                rajpal(at-sign)griggs.dartmouth.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.bitnet, hutchinson(at-sign)macalstr.edu,
                lovasz-laszlo(at-sign)cs.yale.edu, plock(at-sign)stlawu.bitnet, 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,
                krg(at-sign)rover.wellesley.edu, Rhoades(at-sign)emmy.smith.edu, hull(at-sign)cs.uri.edu,
                rajpal(at-sign)dartmouth.edu, silbergd(at-sign)snynewvm.bitnet

REVISED SCHEDULE  FOR:

               the seventeenth one day conference on

                     Combinatorics and Graph Theory

                      Saturday, November 11, 1995

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

                               Schedule

10:00  Esther Tesar (Drew University)
        Some Extensions of the Genus Distribution of
         Closed-End Ladders

11:10   Laszlo Lovasz (Yale University)
	     The Matching Structure of Graphs

12:10  Lunch

 2:00  Joe Bonin (George Washington University)
        A Survey of Dowling Lattices

 3:10 NEW TALK:: Ileana Streinu (Smith College)
        Visibility in Pseudo-Polygons
                 and
        Vertex-Edge Pseudo-Visibility Graphs

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

We have received an NSF grant to support these conferences. This
will allow us to provide a modest transportation allowance to those
attendees who are not local.

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

Karen Collins (Wesleyan Univ.), (203) 685-2169,
kcollins(at-sign)wesleyan.edu

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

Date:           Wed, 8 Nov 1995 16:29:41 -0500 (EST)
From:           Jim Propp <propp(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        Bona, 11/15

Wednesday, November 15, 4:35 p.m.; MIT, room 2-338

			 Miklos Bona (MIT)

		Permutations avoiding certain patterns 

It is a long-studied, hard problem to determine how many permutations 
in S_n avoid a certain pattern q.  The general conjecture claims that 
less than K^n, where K is a constant. Efforts to prove this have been
unsuccessful for most patterns.  (For two permutations a and b, it is 
NP-complete to decide whether a is a pattern of b; the problem of 
counting permutations in S_n avoiding q is #P-complete. Thus in general
all we can expect is an upper bound or an asymptotical formula, not an 
exact formula).  The only important cases in which the conjecture is 
known to be true were when k = 3 or when the pattern is monotonic.  We 
improve these results showing that the_conjecture_on_the_exponential_
upper_bound_is_true_for_all_patterns_of_length_4.

A conjecture states that if S_n(q_1) < S_n(q_2) for some n, then this 
inequality holds for all N > n.  We prove this conjecture for patterns
of length 4.  These are the first results proving that one pattern is 
more likely to occur in a random permutation than another one.  (Even 
in the asymptotical sense).  Finally, we prove a lemma which allows us 
to extend our results to some longer patterns. 

Date:           Wed, 8 Nov 1995 19:22:01 -0500 (EST)
From:           Jim Propp <propp(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        Jackson, 11/17

Friday, November 17, 4:15 p.m.; MIT, room 2-338

			David Jackson (Waterloo)

	The genus series for monopoles and the Euler characteristic 
	       for the moduli spaces of real algebraic curves

This question was solved for the complex case in 1986 by Harer and Zagier. 
A later argument was given by Penner.  The real case, however, has remained 
open.  In this talk I will give two arguments, that are combinatorial 
ones, which appeal 2-cell embeddings of graphs.

The first argument is based on determining the genus series for monopoles 
(these are maps with one vertex) in locally orientable surfaces.  This is 
of interest in its own right.

The moduli space question can be expressed as a particular monopole problem 
(joint work with Goulden and Harer).  This second problem can be treated by 
a classical theorem about multivariate integrals, to give a very simple 
explicit expression for the Euler characteristic.

The integral representation for the case of orientable surfaces can also 
be given, and this gives a proof of the original result of Harer and Zagier 
that is direct.

From:           eaton(at-sign)cs.uri.edu
Date:           Thu, 9 Nov 1995 10:05:41 +0100
To:             lvsnyder(at-sign)amherst.edu, zamfi(at-sign)roz.hunter.cuny.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, btesar(at-sign)mail.cog.jhu.edu,
                mloebl(at-sign)jeeves.uwaterloo.ca, JBONIN(at-sign)gwuvm.gwu.edu, rejam(at-sign)clemson.edu,
                peterrc(at-sign)wpi.edu, jziu(at-sign)maristb.marist.edu, lawsonn(at-sign)cs.rpi.edu,
                mathman(at-sign)brick.purchase.edu, ftbbb(at-sign)cunyvm.edu, spaletaj(at-sign)wpi.wpi.edu,
                elkies(at-sign)abel.math.harvard.edu, emann(at-sign)fas.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)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(at-sign)gwuvm.bitnet, innes(at-sign)cs.uri.edu,
                mcrystal(at-sign)bbn.com, finizio(at-sign)uriacc.uri.edu, macula(at-sign)geneseo.bitnet,
                kcirino(at-sign)lynx.dac.neu.edu, propp(at-sign)math.mit.edu, rstan(at-sign)math.mit.edu,
                combinatorics(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)eagle.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,
                girkar(at-sign)freya.cs.umass.edu, grupen(at-sign)freya.cs.umass.edu,
                guruvado(at-sign)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,
                lory(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, adean(at-sign)skidmore.edu, jzca(at-sign)marist.bitnet,
                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,
                llangley(at-sign)carbon.denver.colorado.edu, Tom.Sundquist(at-sign)dartmouth.edu,
                rajpal(at-sign)griggs.dartmouth.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.bitnet, hutchinson(at-sign)macalstr.edu,
                lovasz-laszlo(at-sign)cs.yale.edu, plock(at-sign)stlawu.bitnet, 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,
                krg(at-sign)rover.wellesley.edu, Rhoades(at-sign)emmy.smith.edu, hull(at-sign)cs.uri.edu,
                rajpal(at-sign)dartmouth.edu,
                "silbergd(at-sign)snynewvm.bitnet X-Envelope-To":apost(at-sign)math.mit.edu,
                ariki(at-sign)math.mit.edu, bona(at-sign)math.mit.edu, cathan(at-sign)math.mit.edu,
                combinatorics(at-sign)math.mit.edu, dfinberg(at-sign)math.mit.edu, djk(at-sign)math.mit.edu,
                fomin%(at-sign)math.mit.edu, lpachter(at-sign)math.mit.edu, mshimo(at-sign)math.mit.edu,
                propp(at-sign)math.mit.edu, rstan(at-sign)math.mit.edu, sara(at-sign)math.mit.edu,
                satomi(at-sign)math.mit.edu
Subject:        Smith College One day conference participants

Mike Albertson
Smith College
Northampton, MA 01063
413-585-3865
Albertson(at-sign)smith.smith.edu

Joseph A. Alfano
Assumption College
Department of Mathematics
500 Salisbury Street
Worcester, MA 01615-0005
(508) 767-7561
jalfano(at-sign)eve.assumption.edu 

Kenneth Appel
University of New Hampshire
Department of Mathematics, Kingsbury Hall, Durham NH 03824
(603) 862-2673
kia(at-sign)oregano.unh.edu

Dan Archdeacon
The University of Vermont  
16 Colchester Ave Burlington VT 05405
802-656-0850
dan.archdeacon(at-sign)uvm.edu

Sanjoy Baruah
The University of Vermont
Dept of CS&EE, 351 Votey Building
The University of Vermont
Burlington, Vt 05405.
(802)656-2547.
sanjoy(at-sign)cs.uvm.edu

Donna Beers
Mathematics Department
Simmons College
Boston, MA 02115
617-521-2389
dbeers(at-sign)vmsvax.simmons.edu

M. K. Bennett
U. Mass.
Department of Mathematics and Statistics
University of Massachusetts
Amherst, MA 01003
413-549-0545
bennett(at-sign)math.umass.edu

Andrew Beveridge
Department of Mathematics
Yale University
New Haven, CT 06520
beveridg(at-sign)pascal.math.yale.edu

Ken Bogart  
Dartmouth College
Mathematics Department
6188 Bradley Hall
Hanover, NH 03755-3551
603-646-3178
k.p.bogart(at-sign)dartmouth.edu

Lynne M. Butler
Haverford College
Department of Mathematics
Stokes Hall 
Haverford College
Haverford, PA 19041
(610) 896-1300 office
(610) 642-7877 home
lbutler(at-sign)haverford.edu

Seth Chaiken
SUNY at Albany
Computer Science Department LI-67A
SUNY at Albany
Albany, NY 12222
518-442-4282
sdc(at-sign)cs.albany.edu

Peter R.Christopher
Worcester Polytechnic Institute
Worcester,MA 01609
508-831-5269
peterrc(at-sign)wpi.edu
 
Kristine Cirino
Northeastern University
Department of Mathematics
Northeastern University
Boston, MA  02115
(617)373-2450
kcirino(at-sign)lynx.neu.edu

Karen L. Collins
Wesleyan University
Department of Mathematics
Middletown CT 06459-0128
(203) 685-2169
kcollins(at-sign)wesleyan.edu
 
Ethan M. Coven
Wesleyan University
Department of Mathematics
Wesleyan University
Middletown, CT  06459-0128
203-685-2204
ecoven(at-sign)wesleyan.edu

Lenore Cowen 
Johns Hopkins University
Dept. of Math. Sciences, Maryland Hall, JHU,
Baltimore, MD 21218
(410) 516-7043
cowen(at-sign)brutus.mts.jhu.edu

Alice M. Dean
Skidmore College
Mathematics and Computer Science Department
Saratoga Springs, NY 12866
518-584-5000, ext. 2371
adean(at-sign)skidmore.edu

Nathaniel Dean
AT&T Bell Laboratories
Room 2C-415
600 Mountain Avenue
Murray Hill, NJ 07974
Phone: 908-582-4190
Fax: 908-582-7550
nate(at-sign)research.att.com

Nancy Eaton
Department of Mathematics
University of Rhode Island
Kingston, RI 02881
(401) 792-4439
eaton(at-sign)math.uri.edu

Li Feng
Department of Mathematics
Wesleyan University
Middletown CT 06459
(203)685-2165
LFENG(at-sign)EAGLE.WESLEYAN.EDU

Norman J. Finizio
University of Rhode Island
Department of Mathematics, URI, Kingston, RI 02881
(401) 792-4430
finizio(at-sign)uriacc.uri.edu

Susanna Fishel
Southern Connecticut State University
Math Department
SCSU
501 Crescent Ave
New Haven, CT 06515
(203) 397-5579 office
fishel(at-sign)scsud.ctstateu.edu

Deborah S. Franzblau
Rutgers University
DIMACS, PO Box 1179, Piscataway NJ  08855
908-445-4573
franzbla(at-sign)dimacs.rutgers.edu

Richard Goldstone
Department of Mathematics
Marist College
290 North Road
Poughkeepsie, NY 12601
richard.goldstone(at-sign)marist.edu
work phone: (914) 575-3000 x2613
home phone: (914) 473-3797

Ruth Haas
Smith College
Department of Mathematics, Northampton, MA 01063
(413) 585-3872
rhaas(at-sign)smith.smith.edu

Barbara Heiles
Wesleyan University
Math Dept, Wesleyan University
Middletown, CT 06459
(203)685-2167
bheiles(at-sign)wesleyan.edu

Jeffrey Allan Hall      	
Department of Mathematics
University of New Hampshire
Durham, NH 03824
(603) 862-2715
http://www.math.unh.edu/~jah	
jah(at-sign)spicerack.unh.edu

Pavol Hell
Simon Fraser University
School of Computing Science, SFU, Burnaby, B.C., Canada V5A1S6
604-291-3391
pavol(at-sign)cs.sfu.ca

Thomas Hull
Dept. of Mathematics
University of Rhode Island
Kingston, RI 02881-0816

Joan P. Hutchinson
Macalester College
Department of Mathematics and Computer Science,
Macalester College, 
St. Paul  MN 55105
612-696-6134
hutchinson(at-sign)macalstr.edu

Duncan Innes 
University of Rhode Island
134 Graduate Village
(401) 792-4223
innes(at-sign)cs.uri.edu

Robert E. Jamison
Department of Mathematical Sciences
Clemson University
Clemson, SC  29634-1907
rejam(at-sign)clemson.edu
OFFICE: (803) 656-5219
FAX: (803) 656-5230

Emelie Kenney
Department of Mathematics
Siena College
Loudonville, NY 12211
(518) 783-2913
kenney(at-sign)siena.edu

John W. Kennedy
Department of Mathematics
Pace University
Pace Plaza
New York, NY 10038
(718)224-8595
kennedyf(at-sign)pacevm.dac.pace.edu

Susan Landau
UMass
Computer Science, UMass, Amherst, MA 01003
413-545-0263
landau(at-sign)cs.umass.edu

Jim Lewis
Univ. of R.I.
Math Dept, Tyler Hall
Kingston, RI 02881
792-4430
jlewis(at-sign) uriacc.uri.edu

Yanxi Liu
University of Mass.
15 Kennedy Drive
Hadley, MA 01035
413-545-2303 (O)
413-549-6911 (H)
liu(at-sign)cs.umass.edu

Patti Frazer Lock
St. Lawrence University
Dept. of Mathematics
St. Lawrence University
Canton, NY  13617
315-379-5292
plock(at-sign)vm.stlawu.edu

Laszlo Lovasz
Yale University, Dept. of Computer Science
New Haven, CT 06520
203-432-1245
lovasz(at-sign)cs.yale.edu

Ross McConnell
Amherst College
Department of Math and Computer Science, Amherst College,
Amherst, MA 01002
(413)-542-7913
ross(at-sign)cs.amherst.edu

Cathy McGeoch
Amherst College
Amherst,  MA 01002
413-542-2414  (For now; will change in 2 weeks)
ccm(at-sign)cs.amherst.edu 

Kathy McKeon
Connecticut College
Conn College Box 5561
270 Mohegan Ave
New London, CT  06320-4196
203-439-2012
kamck(at-sign)conncoll.edu

Sergio Rajsbaum
MIT Laboratory for Computer Science, NE43-367
545 Technology Square
Cambridge, MA 02139
Ph: (617) 253 5905
    (617) 623 3325 (home)
Fax:(617) 253 3480
E-mail: rajsbaum at theory.lcs.mit.edu

Donald Silberger
Department of Mathematics & Computer Science
State University of New York
New Paltz, NY 12561
Phones:  (914)-257-3557  (at SUNY)
              -255-8819  (at home)
E-mail:  SILBERGD(at-sign)NPVM.NEWPALTZ.EDU

Sylvia Silberger
Wesleyan University
Math Dept.
Wesleyan University
Middletown, CT  06459
(203)685-2167
SSilberger(at-sign)eagle.wesleyan.edu

Gara Pruesse
Dept of Computer Science and Electrical Engineering
Votey Building
University of Vermont
Burlington, VT 05405-0156
(802) 656-2538 office
(802) 656-0696 fax
e-mail:  gara(at-sign)cs.uvm.edu

Louis V. Quintas
Pace University
Mathematics Department, New York, NY 10038
Phone: (212) 346 1280
e-mail Address: quintas(at-sign)pacevm.dac.pace.edu

Kathleen Romanik
DIMACS Center for Discrete Mathematics and Theoretical Computer Science
Rutgers University
P.O. Box 1179
Piscataway, NJ 08855-1179
(908) 445-4576
romanik(at-sign)dimacs.rutgers.edu

Lauren Rose
Wellesley College
Math Department/Science Center
Wellesley College
Wellesley, MA 02181
phone number: 617-283-3114
e-mail address: lrose(at-sign)wellesley.edu or lrose(at-sign)molly.wellesley.edu
 
Arnold L. Rosenberg
University of Massachusetts
Department of Computer Science
Amherst, MA 01003
413/545-2743
rsnbrg(at-sign)cs.umass.edu

Joe J. Rushanan
The MITRE Corporation, MS E025
202 Burlington Road
Bedford, MA 01730-1420
(617) 271-2320
jjr(at-sign)mitre.org

Ed Sandifer
Western Connecticut State University
Math/CS Department
Danbury, CT 06810
(203) 426-5326
sandifer(at-sign)wcsu.ctstateu.edu

rodica simion
dept of mathematics
george washington university
washington,  dc 20052
(202) 994 6238
simion(at-sign)gwuvm.gwu.edu

Richard Stanley
MIT
Department of Mathematics 2-375
Cambridge, MA 02139
(617) 253-7930
rstan(at-sign)math.mit.edu

Ileana Streinu
Computer Science Department
Smith College
Northampton, MA 01063
Phone: 413-585-3827
email: streinu(at-sign)cs.smith.edu

Thomas Sundquist
Dartmouth College
HB 6188, Hanover NH, 03755
(603) 646-1590
Tom.Sundquist(at-sign)dartmouth.edu

Steve Tanny
Department of Mathematics
University of Toronto
Toronto, Ontario Canada
M5S 1A1
tanny(at-sign)math.toronto.edu

Ann Trenk
Mathematics Department 
Wellesley College
Wellesley, MA     02181
(617) 283-3140
atrenk(at-sign)wellesley.edu
[On sabbatical at DIMACS in 95-96.  Email will be forwarded.]
 
David C. Vella  
Skidmore College
Dept. Mathematics & Computer Science
Saratoga Springs, NY 12866
518-584-5000; ext. 2364
dvella(at-sign)skidmore.edu

Kati Vesztergombi
Yale University, Dept. of Mathematics
New Haven, CT 06520
203-432-4682
kati(at-sign)math.yale.edu

Evan Wantland
Dept of Math and CS
WCSU
181 White St
Danbury, CT 06810
203 837 9355
wantland(at-sign)mcs1.wcsu.ctstateu.edu

Date:           Wed, 15 Nov 1995 11:04:40 -0500 (EST)
From:           Sergey Fomin <fomin(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        Kalai, 11/20

                APPLIED MATHEMATICS COLLOQUIUM

SPEAKER:        Gil Kalai
                Institute for Advanced Study and Hebrew University

TOPIC:          All Monotone Graph Properties Have Sharp Thresholds

ABSTRACT:

In their seminal work which initiated random graph theory Erd\"os and
R\'enyi discovered that many graph properties have sharp thresholds as the
number of vertices tends to infinity.  That is, if every edge of the graph
is chosen with probability $p$, then when $p$ increases, the transition
from a property being very unlikely to its being very likely is very
swift.

We prove a conjecture of Linial that every monotone graph property has a
sharp threshold. This result applies to random subgraphs of arbitrary
symmetric graphs.  We will discuss the relation between the symmetry group
and the length of the transition interval.

DATE:           Monday, November 20, 1995

TIME:           4:15 p.m.

LOCATION:       Building 2 -- Room 105

REFRESHMENTS WILL BE SERVED FROM 3:45 P.M. IN BUILDING 2, ROOM 349.   

Date:           Fri, 17 Nov 1995 10:58:26 -0500
From:           kcollins(at-sign)MAIL.WESLEYAN.EDU (Karen L. Collins)
Subject:        spring dates and website
To:             kcollins(at-sign)MAIL.WESLEYAN.EDU

Dear CONE mailing list,

We have set the dates for the spring meetings at Smith College.  They are:

Sunday, February 4, 1996

Saturday, March 30, 1996

Saturday, April 27, 1996

The speakers for the February 4th meeting will be:  Ethan Coven,
Danny Kleitman, Emily Petrie, and Joe Rushanan.  We will send
out an announcement with titles in early January.

We now have a Website for the CONE meetings.  The address is

http://math.smith.edu/~rhaas/coneweb.html

The table of contents of the Web site is:  dates of future meetings,
schedule for next meeting, directions to Smith College, schedules of past
meetings, abstracts of talks, papers available electronically, names and
addresses of participants, other websites of interest to combinatorists,
and the Smith College Mathematics Department page.  We hope you will
find it useful.

Date:           Mon, 20 Nov 1995 22:18:42 -0500 (EST)
From:           Jim Propp <propp(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        Free-for-all, 11/29

Wednesday, November 29, 4:35 p.m.; MIT, room 2-338

		All of Us (from All Over the Boston Area)

	     Open Mike Session / Combinatorial Free-for-All

Here's another chance to share partial results, open questions,
and nice ideas that aren't suited to the 50-minute talk format.
Presenters will include Gian-Carlo Rota, Dan Kleitman, and
Christos Athanasiadis.  Let Jim Propp know ahead of time what 
you're bringing, if you plan on presenting something that will 
take longer than five minutes (propp(at-sign)math.mit.edu; 253-6544).

Date:           Mon, 20 Nov 1995 22:20:54 -0500 (EST)
From:           Jim Propp <propp(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        MIT Combinatorics Seminar: December schedule

		    MIT COMBINATORICS SEMINAR

Here is a list of talks currently scheduled for the month of December.
Notice that talks scheduled on *Wednesdays* will begin at *4:35* p.m., 
but that talks scheduled on *Fridays* will begin at *4:15*.

Wednesday, December 6, 4:35 p.m.: Gian-Carlo Rota,
	A formal theory of resultants, I: The Cliffordization of Hopf algebras

Friday, December 8, 4:15 p.m.: Gian-Carlo Rota,
	A formal theory of resultants, II: Explicit formulas for resultants

Wednesday, December 13, 4:35 p.m.: Heidi Burgiel,
	Symmetric embeddings of regular maps: regular skew polyhedra

All talks will meet in room 2-338.

Date:           Fri, 1 Dec 1995 00:41:05 -0500 (EST)
From:           Jim Propp <propp(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        Rota, 12/6 *and* 12/8

Wednesday, December 6, 4:35 p.m.; MIT, room 2-338
	*and*
Friday, December 8, 4:15 p.m.; MIT, room 2-338

		    Gian-Carlo Rota (MIT)

		A formal theory of resultants

Part I: The Cliffordization of Hopf algebras

Part II: Explicit formulas for resultants

A formula for the resultant of n homogoneous polynomials will be given.
This formula can be used to derive all known properties of resultants
without recourse to elimination theory.

Those who attend are expected to know basic notation of Hopf algebras.

Date:           Wed, 6 Dec 1995 08:00:19 -0500 (EST)
From:           Jim Propp <propp(at-sign)math.mit.edu>
To:             combinatorics(at-sign)math.mit.edu
Subject:        Burgiel, 12/13 (last meeting of semester)

Wednesday, December 13, 4:35 p.m.; MIT, room 2-338

		Heidi Burgiel (Geometry Center)

              Symmetric embeddings of regular maps:
                     regular skew polyhedra

The label "regular polytope" can be applied to objects ranging from
Platonic solids to simplicial complexes.  The object of this talk is
to describe methods of taking regular maps --- regularly tiled
2-manifolds --- and embedding the vertices of the tilings in Euclidean
space to form objects called regular skew polyhedra.  These polyhedra
have all the symmetries dictated by the automorphism group of the
underlying manifold, but may not have planar faces.  They need not
even lie in three dimensional space!

For example, a sphere can be regularly tiled with pentagons.  One
realization of this map is the dodecahedron.  More interestingly, a
torus can be tiled with squares.  As Coxeter and Petrie discovered in
1926, this map can be realized in four dimensions as a polyhedral
surface with square faces and "skew square" vertex figures.

In my talk I will describe more skew polyhedra, and review the methods
I used to discover them.  These methods, involving association schemes
and representation theory, can be extended to provide symmetric
realizations of any graph or polytope whose automorphism group is
vertex-transitive.