New York Combinatorics Seminar

Sponsored by the Graduate Center's Math Department and Computer Science Department

Fridays 11:45 am - 12:45 am in Room 4419

This seminar covers a wide range of topics in combinatorics and its applications.

The CUNY Graduate Center is located at 365 Fifth Avenue (at the corner of 34th Street), New York. It can be easily reached by subway using the B,D,F,N,Q,R, or 6 train.

Seminar Co-Organizers:
CUNY: Nadia Benakli (City Tech) Ezra Halleck (City Tech), Sandra Kingan (Brooklyn College), Joseph Malkevitch (York College), Kerry Ojakian (BCC), Mingxian Zhong (Lehman College),
Montclair State University: Deepak Bal, Jonathan Cutler
Hofstra University: Kira Adaricheva, Eric Rowland

Spring 2019 Talks

Feb 15, 2019: Nadia Benakli (New York City College of Technology)

Title: k-neighborhood degree list of a graph
Abstract: The k-neighborhood degree list of a vertex v in a graph G, denoted by N_kDL(v), is the list of degrees of vertices at distance k from v. In this talk I will present some results for 2-neighborhood degree lists. A 2-switch operation that preserves degrees is the replacement of a pair of edges v1v2 and w1w2 such that deg(v1)=deg(w1) and deg(v2)=deg(w2) by the edges v1w2 and v2w1, given that they did not appear in the graph originally. Building on results by Barrus and Donavan (Discrete Mathematics 341(2018)) and Bassler et al (New J. Phys. 17(2015)), I will prove that within the class of diameter 2 graphs, the 2-switch operation that preserves degrees also preserves 2-neighborhood degree lists. Then I will present a generalization of this operation that preserves 2-neighborhood degree lists in any graph. This is joint work with E. Halleck and S. Kingan.

Mar 1, 2019: Shahriar Shahriari (Pomona College)

Title: Combinatorics of Posets of Subspaces
Abstract. Let V be a finite dimensional vector space over a finite field, and consider the poset of subspaces of V ordered by inclusion. The combinatorial properties of this partially ordered set often resemble those of the Boolean lattices, the subsets of a finite set ordered by inclusion. Often the case of subsets is easier to handle, but, there are situations where a combinatorial question is easier to answer for subspaces. In this talk, we discuss a few combinatorial problems in the poset of subspaces including forbidden configuration problems: Given a small poset P, what is the largest number of subspaces of V that do not contain a copy of P? The latter is joint work with Song Yu.

Mar 8: Pawel Pralat (Ryerson University, Toronto, Canada)

Mar 15, 2019: Rigoberto Florez (The Citadel)

Mar 22, 2019: Yigal Kamel (Cooper Union)

Mar 29, 2019: Alexander McDonough (Brown University)

Apr 5, 2019: Alex Kodess (SUNY Farmingdale)

Apr 12, 2019:

May 3, 2019:

Previous Co-Organizers

Christopher Hanusa (Spring 2011 - Spring 2015)

Previous Speakers

Fall 2018
Spring and Summer 2018
Fall 2017
Spring 2017
Fall 2016
Spring 2016
Fall 2015
Spring 2015
Fall 2014
Spring 2014
Fall 2013
Spring 2013
Fall 2012
Spring 2012
Fall 2011
Spring 2011
Previous Talks hosted by Janos Pach