Department of Mathematics

University of Mississippi

Combinatorics Seminar

Friday, November 21, 2014, 3:00-3:50 PM, Hume 331.

Jie Ma
Carnegie Mellon University/USTC

Digraph Coloring and Forbidden Cycle (pdf)

Friday, November 14, 2014, 2:00-2:50 PM, Hume 331.

Richard Johnson
University of Memphis

The Robber Locating Game (pdf)

Wednesday, October 29, 2014, 3:00-3:50 PM, Hume 322.

Tomas Juskevicius
University of Memphis

On a conjecture of Leader and Radcliffe related to the Littlewood-Offord problem (pdf)

Wednesday, November 5, 2014, 3:00-3:50 PM, Hume 331.

Dominik Vu
University of Memphis

Combinatorial search and separating families (pdf)

Wednesday, October 29, 2014, 3:00-3:50 PM, Hume 322.

Tomas Juskevicius
University of Memphis

On a conjecture of Leader and Radcliffe related to the Littlewood-Offord problem (pdf)

Friday, October 10, 2014, 2:00-2:50 PM, Hume 331.

Dong Ye
Middle Tennessee State University

Decomposing cubic graphs with low genus (pdf)
It was conjectured by Ho man-Ostenhof that the edge set of every cubic graph can be decomposed into a spanning tree, a matching and a family of cycles. We prove the conjecture for 3-connected cubic graphs with low genus. Our method provides a polynomial time algorithm to nd the decomposition.

Friday, September 26, 2014, 3:00-3:50 PM, Hume 331.

Vladimir Nikiforov
University of Memphis

Some analytic methods for hypergraphs (pdf)
This talk will present an analytic approach for studying hypergraphs. The roots of the method are in the spectral theory for 2-graphs and in the theory of variational spectra of hypermatrices. The basic concepts of the method give a single viewpoint to a number of problems in hypergraphs, erasing the dierences between spectral and nonspectral results. The approach is particularly appropriate for extremal problems; for example it allows to prove that spectral extremal problems for hypergraphs are asymptotically equivalent to the corresponding edge extremal problems. This talk is not too technical and it should be interesting for a wider audience.

Wednesday, September 17, 2014, 3:00-3:50 PM, Hume 331.

James Reid
University of Mississippi

The Matroids Without a Small Minor (pdf)
This talk includes an introduction to Matroid Theory, an exposition of classical results on graph minors, and extensions of these results from graphs to matroids. Joint work with Kayla Harville and Haidong Wu is presented on excluded minors in the classes of regular and binary matroids. The proofs of these results are both theoretical and computer-based.

Wednesday, September 10, 2014, 3:00-3:50 PM, Hume 331.

Haidong Wu
University of Mississippi

Characterizing 3-connected binary matroids with no P9-minor (pdf)
Kuratowski’s Theorem states that a graph is planar if any only if it has no minor that is isomorphic to K3,3 or K5. Mayhew, Royle and Whittle characterize internally 4-connected binary matroids with no M(K3,3)-minor. Oxley characterizes 3-connected binary matroids without any P9- or P∗9-minor. In this paper, we give a complete characterization of 3-connected binary matroids with no P9-minor. Such a matroid is either one of the non-regular minors of a special 16-element matroid Y16; a 3-connected regular matroid; a binary spike with rank at least four; or is a matroid in an infinite class of matroids called starfishes. This is joint work with Guoli Ding at LSU.

Wednesday, September 3, 2014, 3:00-3:50 PM, Hume 331.

Hehui Wu
University of Mississippi

Triangle-free subgraph with high fractional chromatic number (pdf)
A classic theorem states that for any k and l, there exists a graph with girth at least l, and chromatic number at least k. In 1970’s, Erd˝os and Hajnal proposed a conjecture that for any k, l, there exists a number f(k,l), such that if G has chromatic number at least f(k,l), then it contains a subgraph with chromatic number at least k and girth at least l. In 1977, Rödl proved that it is true for l = 3, that is, if the chromatic number is sufficiently large enough, that it contains a triangle-free subgraph with large chromatic number. Recently, we proved an analogous result for fractional chromatic number: for any k, there exists a f(k), such that if the fractional chromatic number is at least f(k), then it contains a triangle-free subgraph with fractional chromatic number at least k. This is joint work with Professor Bojan Mohar at Simon Fraser University.

Friday, November 15, 2013, at 2:00 PM, in Hume 331.

John Estes
Belhaven University

Hamiltonian cycles through a given edge of more than 1-tough chordal planar graphs (pdf)

Friday, October 18, 2013, at 1:50 PM, in Hume 331.

Shaohui Wang
The University of Mississippi
Multiplicative Zagreb indices of k-trees (pdf)

Monday, June 10, 2013, 1:00-1:50pm, Hume 331.

Jinko Kanno
Louisiana Tech University

Genus and Other Graph Invariants (pdf)
The minimal non-embeddable graphs for the torus are unknown (numerous). It may be a good approach to break the toroidal graphs into tractable subclasses and nd obstructions or some characterizations for each subclass. Those subclasses can be: H-minor free toroidal graphs with a small graph H, or the classes having the same number for some graph invariants including non-orientable genus, thickness, outer-thickness, or possibly the essential curve number for toroidal graphs, which will be introduced in this talk.

Tuesday, April 16, 2013, 1:00-1:50pm, Hume 331.

Chris Rodger
Auburn University

Amalgamations and Hamilton Decompositions (pdf)

Wednesday, April 3, 2013 at 3:00-3:50pm, Hume 331.

William Staton
University of Mississippi

k-Trees, k-Frames, Shells and Independence Polynomials (pdf)

Friday, March 22, 2013, 2:00-2:50pm, Hume 331.

Stan Dziobiak
University of Mississippi

On Excluded and Unavoidable Minors in Graphs (pdf)

Monday, March 4, 2013, 3:00-3:50pm, Hume 331.

James Shook
National Institute of Standards and Technology

Math at the National Institute of Standards and Technology (pdf)

Friday, November 2, 2012, 2:00-2:50pm, Hume 331.

Kayla Davis Harville
University of Mississippi

On Regular and Binary Matroids Without Small Minors (pdf)

Monday, September 17, 2012, 2:00-2:50pm, Hume 331.

Hehui Wu
McGill University, Canada

Nearly Tight Linear Programming Bounds for Demand Matching in Bipartite Graphs (pdf)

Friday, April 20, 2012, 1:00-1:50pm, Hume 331.

Jaromy Kuhl
University of West Florida

Complete tripartite graphs and their competition numbers (pdf)

April 4, 2012, 3:00-3:50pm, Hume 331.

Emlee Nicholson
Millsaps College

Degree sum condition for k-ordered hamiltonian connected graphs (pdf)

Wednesday, March 28, 2012 at 3:00 pm in Hume 331.

Wanda Payne
University of Mississippi

Well-covered k-trees, k-frames, and unique colorability (pdf)

Thursday, January 19, 2012 at 2:00 pm in Hume 331.

Hehui Wu
McGill University, Canada

Longest Cycles in Graphs with Given Independence Number and Connectivity (pdf)

Thursday, December 1, 2011 at 1:50 pm in Hume 331.

Stan Dziobiak
University of Mississippi

Using Mathematica for Graph Theoretical Computations (pdf)

Thursday, October 6, 2011 at 1:50 pm in Hume 331.

James Shook
National Institute of Standards and Technology

Affiliation Networks (pdf)

Thursday, September 8, 2011 at 1:50 pm in Hume 331.

Stan Dziobiak
University of Mississippi

3-Connected Graph of Path-Width at Most Three (pdf)

Thursday, May 12, 2011 at 3:00 pm in Hume 331.

James Shook
University of Mississippi

On Finding a Minimum Toughness Condition for a k-Tree to be Hamiltonian (pdf)

Monday, April 18, 2011 at 3:00 pm in Hume 331.

Cameron Byrum
University of Mississippi

How Many Holes Can an Unbordered Partial Word Contain?

Wednesday, April 13, 2011 at 3:00 pm in Hume 331.

Zhiquan Hu
Central China Normal University

Linked Graph with Modular Constraints (pdf)

Friday, April 1, 2011 at 3:00 pm in Hume 331.

James Reid
University of Mississippi

On a class of matroid designs (pdf)

Wednesday, November 17, 2010 at 2:00 pm in Hume 331.

Bruce Priddy
University of Mississippi

Domination and Independent Domination in Graphs (pdf)

Thursday, October 28, 2010 at 2:00 pm in Hume 321.

Guantao Chen
Georgia State University

Long Cycles in 3-Connected Graphs with Bounded Degrees (pdf)

Friday, October 22, 2010 at 2:00 pm in Hume 331.

Xuechao Li
University of Georgia

Lower Bounds of Edge Critical Graphs (pdf)

Tuesday, June 24, 2010 at 3:00 pm in Hume 331.

Manoel Lemos
Universidade Federal de Pernambuco, Brazil

On triangle-free 3-connected matroids (pdf)

Wednesday, April 28, 2010 at 3:00 pm in Hume 331.

Xiaojuan Li
Urumqi Vocational University, China

Some results on path-factors in graphs (pdf)

Colloquium
Friday November 20, 2009 at 2:15 pm in Hume 331.

Michal Karonski
Adam Mickiewicz University, Poland

On the 1-2-3-conjecture (pdf)

Monday October 12, 2009 at 2:00 pm in Hume 331.

Xiangqian Zhou
Wright State University

Clones in representable matroids over a finite field (pdf)

Friday October 9, 2009 at 2:00 pm in Hume 331.

William Staton
University of Mississippi

On the shell of some graphs (pdf)

Monday, July 27, 2009 at 2:00pm in Hume 331.

Sivan Altinakar
École Polytechnique, Montréal, Canada

On compact edge-colorings : a polynomial time reduction from k-linear to k-cyclic (pdf)

Wednesday, March 11, 2009 at 1:00pm in Hume 331.

Hao Li
LRI, UMR8623 CNRS and Universite Paris-sud 11

Cycles and subsets of vertices in graphs (pdf)

Wednesday, February 25, 2009 at 2:00pm in Hume 331.

James Reid
University of Mississippi

On minimally k-connected matroids (pdf)

Wednesday, February 11, 2009 at 2:00pm in Hume 331.

Sandra Spiroff
University of Mississippi

A Comparison of Zero Divisor Graphs (pdf)

Wednesday, January 14, 2009 at 2:00pm in Hume 331.

Carolyn Chun
Louisiana State University

A chain theorem for internally 4-connected matroids (pdf)

Wednesday, January 14, 2009 at 3:00pm in Hume 331.

Deborah Chun
Louisiana State University

Deletion-Contraction Polynomials (pdf)

Wednesday, December 3, 2008 at 3:00pm in Hume 331.

Xianqian Zhou
Wright State University

Signed Graphs and Their Matroids (pdf)

Friday, October 31, 2008 at 2:00pm in Hume 331.

James Shook
University of Mississippi

A characterization of the Centers of Chordal Graphs (pdf)

Friday, October 24, 2008 at 2:00pm in Hume 331.

James Reid
University of Mississippi

On Circuit Sizes of Binary Matroids (pdf)

Wednesday, September 5, 2007.

Haidong Wu
University of Mississippi

Non-separating co-circuits in 3-connected binary matroids (pdf)

Thursday, September 22, 2005 in Hume Hall 331 at 1:00pm.

Lei Cao
University of Mississippi

Decoding of Huffman codes with self-synchronization strings (pdf)

Thursday, September 8, 2005 in Hume Hall 331 at 1:00pm.

James Reid
University of Mississippi

Recent Results on Clones in Matroids (pdf)

Friday, April 29, 2005 in Hume Hall 331 at 3:00pm.

Hongjian Lai
West Virginia University

Every 6-connected line graph is hamiltonian (pdf)

Friday, April 22, 2005 in Hume Hall 331 at 3:00pm.

R. H. Schelp
University of Memphis

Ramsey Unsaturated and Saturated Graphs (pdf)

Friday, February 18, 2005 in Hume Hall 331 at 3:00pm.

James Reid
University of Mississippi

Clones in Representable Matroids (pdf)

Friday, October 15, 2004 in Hume Hall 331 at 3:00pm.

Jakayla Robbins
University of Mississippi

Orienting the free spikes (pdf)

Friday, October 8, 2004 in Hume Hall 331 at 3:00pm.

Haidong Wu
University of Mississippi

An introduction to the Tutte Polynomial (pdf)

Friday, September 24, 2004 in Hume Hall 331 at 3:00pm.

Laura Sheppardson
University of Mississippi

Graph generations for predictive chemistry (pdf)

Tuesday, Sept.14, 2004 in Hume Hall 331 at 3:00pm.

Manoel Lemos
Federal University of Pernambuco, Brazil

Triads in 3-connected Matroids (pdf)

Wednesday, April 14, 2004 in Hume Hall 331 at 3:00pm.

Guantao Chen
Georgia State University

Plane Graphs with Positive Curvature (pdf)

Wednesday, April 7, 2004 in Hume Hall 331 at 3:00pm.

James Reid
University of Mississippi

“Intersections” of Linearly Largest Circuits in Matroids (pdf)

Wednesday, March 31, 2004 in Hume Hall 331 at 3:00pm.

Xueliang Li
Center for Combinatorics, Nankai University

Trees with Maximum General Randic Index (pdf)

Wednesday, March 24, 2004 in Hume Hall room 331 at 3:00pm.

Xingxing Yu
Georgia Institute of Technology

Bonds in 3-connected Mulitgraphs (pdf)

Wednesday, Feb. 18, 2004 in Hume Hall 331 at 3:00pm.

Klas Markström
Umea University

The Cycle Double Cover Conjecture II (pdf)

Wednesday, Feb. 11, 2004 in Hume Hall 331 at 3:00pm.

Klas Markström
Umea University

An Introduction to Cycle Double Cover Conjecture (pdf)

Wednesday, Feb. 4, 2004 in Hume Hall 331 at 3:00pm.

Bing Wei
University of Mississippi

Chords in Longest Cycles of Graphs (pdf)

Wednesday, January 28, 2004 in Hume Hall 331 at 3:00 pm.

Xiaoya Zha
Middle Tennessee State University

Closed 2-cell Embeddings of Graphs Embeddable in the Projective Plane and the Torus (pdf)

Wednesday, January 21, 2004 in Hume Hall 331 at 3:00 pm.

Xueliang Li
Center for Combinatorics, Nankai University

Recent Results and Problems in General Randic Index (pdf)

Thursday, October 2, 2003 in Hume Hall 331 at 2:00pm.

Josh Hanes
University of Mississippi

On Szemeredi’s Regularity Lemma (pdf)

Thursday, October 16, 2003 in Hume Hall 331 at 2:00pm.

Hongjian Lai
West Virginia University

Group connectivity of a graph (pdf)

Thursday, September 25, 2003 in Hume Hall 331 at 2:00pm.

Laura Sheppardson
University of Mississippi

Planar decomposition of graphs (pdf)

Thursday, September 4, 2003 in Hume Hall 331 at 2:00 pm.

William Staton, Benton Tyler (pdf)
University of Mississippi

An Extremal Problem for Graphs with Large Odd Girth

Thursday, September 18, 2003 in Hume Hall 331 at 2:00pm.

James Reid
University of Mississippi

Job Assisgnment Problems (pdf)

Thursday, August 28, 2003 in Hume Hall 331 at 2:00 pm.

Tristan Denley
University of Mississippi

The Bela Bash (pdf)

Thursday, March 27, 2003 in Hume Hall 331 at 3:00pm.

Bing Wei
University of Mississippi

Graph Minors and Linkages III (pdf)

Thursday, March 20, 2003 in Hume Hall 331 at 3:00pm.

Bing Wei
University of Mississippi

Graph Minors and Linkages II (pdf)

Thursday, February 27, 2003 in Hume Hall 331 at 3:00pm.

Bing Wei
University of Mississippi

Graph Minors and Linkages (pdf)

Thursday, February 13, 2003 in Hume Hall 331 at 3:00pm.

Bing Wei
University of Mississippi

On the total domination number of graphs (pdf)

Thursday, February 6, 2003 in Hume Hall 331 at 3:00pm.

Haidong Wu
University of Mississippi

Chords in Graphs (pdf)

Thursday, January 30, 2003 in Hume Hall 331 at 3:00pm.

William Staton
University of Mississippi

On the Bipartite Density of a Graph (pdf)

Thursday, January 23, 2003 in Hume Hall 331 at 3:00pm.

James Reid
University of Mississippi

On largest bond conjecture in graphs