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: Ezra Halleck (City Tech), Sandra Kingan (Brooklyn College), Joseph Malkevitch (York College), Kerry Ojakian (BCC)
Montclair State University: Deepak Bal, Jonathan Cutler
Hofstra University: Kira Adaricheva

Spring 2018 Talks

Feb 16, 2018: Adam Sheffer (Baruch College, CUNY)

Title: Counting Plane Graphs: Perfect Matchings, Spanning Cycles, and Kasteleyn's Technique

Abstract: We will discuss the maximum number of crossing-free straight-edge spanning cycles (also known as Hamiltonian tours, and as simple polygonizations) that can be embedded over a set of N points in the plane. We derive an improved upper bound for this number by relying on Kasteleyn's linear algebra technique.

More specifically, we bound the ratio between the number of spanning cycles and perfect matchings that can be embedded over a point set and the number of triangulations that can be embedded over it. The respective bounds are O(1.8181^N) for cycles and O(1.1067^N) for matchings. These imply a new upper bound of O(54.543^N) on the number of crossing-free straight-edge spanning cycles that can be embedded over any specific set of N points in the plane.

Feb 23, 2018:

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Mar 2, 2018: Zajj Daugherty (City College, CUNY)

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Mar 9, 2018:

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Mar 16, 2018: Brian Hopkins (Saint Peters University)

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Mar 23, 2018:

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Apr 13, 2018:

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Apr 20, 2018:

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Apr 27, 2018:

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May 4, 2018:

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May 11, 2018:

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May 18, 2018:

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Previous Co-Organizers

Christopher Hanusa (Spring 2011 - Spring 2015)

Previous Speakers

Spring 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