New York Combinatorics Seminar

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

Fridays Noon - 1:00 pm (Online)

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), Megan Owen (Lehman College), Mingxian Zhong (Lehman College).
Montclair State University: Deepak Bal, Jonathan Cutler
Hofstra University: Kira Adaricheva, Eric Rowland

Spring 2021 Talks

The zoom link is
Email any one of the co-organizers for the password. It is the same as last semester.

Sep 3, 2021: Aparna Lakshmanan S. (Cochin University of Science and Technology, India)

Title: Graph Labeling Problems: From Leech Trees to Leech Graphs
Abstract: A graph labeling is a function with some specific properties which assigns values to vertices, edges, or both. Graceful labeling, edge graceful labeling, and harmonic labeling are some of the well know graph labelings. In this talk, I will focus on a special kind of edge labeling called Leech labeling, introduced by John Leech in 1975. Let T be a tree of order n. For any edge labeling f from the edge set E to the natural numbers, the weight of a path P is the sum of the labels of the edges of P and is denoted by w(P). If the weights of the $^nC_2$ paths in T are exactly 1, 2,...,$^nC_2$, then f is called a Leech labeling and a tree which admits a Leech labeling is called a Leech tree. I will discuss some known results in Leech labeling, a new concept called Leech index, and the possibility of extending Leech labeling to general graphs. Some Leech related labeling will also be discussed. This is joint work with S. Arumugam and Seema Varghese.

Sep 24, 2021: Robert Bliss (Rutgers University)


Oct 1, 2021: (Vaidyanathan Sivaraman (Mississippi State University) (


Oct 8, 2021: Michael Barrus (University of Rhode Island)


Oct 15, 2021: Sophie Spirkl (University of Waterloo, Canada)


Oct 22 2021: Abigail Raz (Cooper Union)


Oct 29, 2021: Hailun Zheng (University of Copenhagen, Denmark)


Nov 5, 2021: Aj Bu (Rutgers University)


Previous Co-Organizers

Christopher Hanusa (Spring 2011 - Spring 2015)

Previous Speakers

Spring 2021
Fall 2020
Spring 2020
Fall 2019
Spring 2019
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