Ben Pak Ching Li

E2-479 EITC
Department of Computer Science,
University of Manitoba,
Winnipeg, Manitoba, Canada R3T 2N2

Welcome to my website. I am an associate professor in the Department of Computer Science at the University of Manitoba. My research activities are focused in the areas of combinatorial designs, graph theory and algorithms.

Teaching

I will be teaching the following courses in the upcoming year (2011-2012):

Computer Networks (COMP 3720) and
A graduate course on combinatorial algorithms (COMP 7720).

Courses that I have taught throughout the years.

COMP 1010 - Introduction to Computer Science
COMP 2080 - Analysis of Algorithms
COMP 2130 - Discrete Mathematics for Computer Science
COMP 2140 - Data Structures and Algorithms
COMP 2160 - Programming Practices
COMP 2280 - Introduction to Computer Systems
COMP 3170 - Analysis of Algorithms and Data Structures
COMP 3290 - Introduction to Compiler Construction
COMP 4140 - Introduction to Cyptography and Cryptosystems
COMP 7720 - Combinatorial Algorithms

Research

My research interests lie in three areas:

Combinatorial Designs,
Graph Theory and
Algorithms.

Combinatorial Designs

The types of combinatorial designs that I am most interested in are balanced incomplete block designs, covering designs, Lotto designs, Latin squares, hash families and cover-free families. I study designs from two different aspects: theoretical and algorithmic. I am currently working on a project involving friendship hypergraphs.

Link to my Lotto tables.
Link to files containing all non-isomorphic restricted Savate-Beam triple systems of order 6.
Link to files containing all non-isomorphic Savate-Beam triple systems of order 6.

Graph Theory

I am interested in Hamilton circuits and pancyclism of graphs. Lately, I have been interested in graph labelings, especially antimagic labelings. I have several projects that are currently ongoing in graph labelings.

Algorithms

I am interested in the complexity of problems (NP-Completeness) and approximation algorithms for NP-Hard problems. I also interested in graph algorithms amd algorithms for enumerating combinatorial objects.

Some Recent Publications (from 2006 to current)

Sperner partition systems, with Karen Meagher. Submitted Jan 2012.

Combination labelings of graphs. Submitted Jan 2012.

A note on Hamiltonicity of block intersection graphs of universal-friend friendship hypergraphs. Accepted to appear in JCMCC.

Antimagic labelings of power of cycles graphs. Accepted to Ars Combinatoria (July.23, 2011)

Friendship 3-hypergraphs, with G.H.J. van Rees, S. H. Seo, and N.M. Singhi. Accepted to appear in Discrete Mathematics (February 25, 2012).

Ranking and Loopless Generation of k-ary Dyck Words in Cool-lex Order, with S. Durocher, D. Mondal, and A. Williams. Accepted to IWOCA 2011. (May 19, 2011)

D.W. Hein, P.C. Li. Savate-Beam Triple Systems for v=5 and v=6. Accepted to appear in the Journal of Combinatorial Mathematics and Combinatorial Computing. (May 7, 2010)

The Stein_Lovasz Theorem and its Application to Some Combinatorial Arrays: D. Deng, Y. Zhang, P.C. Li and G.H.J. van Rees. Journal of Combinatorial Mathematics and Combinatorial Computing, 77(2011), 17-32.

P.C. Li, M. Toulouse. Maximum Leaf Spanning Trees for Grid Graphs. Journal of Combinatorial Mathematics and Combinatorial Computing, 73(2010) 181-193.

M.S. Keranen, W.H. Kocay and B. Li, Degree sequence conditions for partial Steiner triple systems. Bulletin of the ICA, 57(2009) 71-73.

C. Dai, B. Li, M. Toulouse, A Multilevel Cooperative Tabu Search Algorithm for the Covering Design Problem. Journal of Combinatorial Mathematics and Combinatorial Computing, 68(2009) 33-66.

P.C. Li., G.H.J. van Rees. Mutually Nearly Orthogonal Latin Squares. Journal of Combinatorial Mathematics and Combinatorial Computing, 62(2007) 13-24.

W.L.Kocay, P.C. Li, On 3-Hypergraphs with Equal Degree Sequences. Ars Combinatoria, 82(2007) 145-157.

D. Deng, D.R. Stinson, P.C. Li, G.H.J. van Rees, R. Wei. Constructions and Bounds for (m,3)-Splitting Systems. Discrete Mathematics, 307(2007), 18-37.

R.T. Bilous, C.W.H. Lam, L.H. Thiel, P.C. Li, G.H.J. van Rees,S.P. Radziszowski, W.H. Holzmann, H. Kharaghani. There is no (22,8,4) Block Design. Journal of Combinatorial Designs, 15 (2007) 262-267.

P.C.Li, G.H.J. van Rees, R. Wei, Constructions of 2-Cover-Free Families and Related Separating Hash Families. Journal of Combinatorial Designs, 14(2006), 423-440.

P.C. Li, M. Toulouse, Variations of the Maximum Leaf Spanning Tree Problem for Bipartite Graphs. Information Processing Letters, 97(2006),129-132.

M. Greig, P.C. Li & G.H.J. van Rees. Covering Designs on 13 Blocks. Utilitas Math. 70(2006) 221-261.

P.C. Li & M. Toulouse. Some NP-Completeness Results on Partial Steiner Triple Systems and Parallel Classes. Ars Combinatoria 80(2006) 45-51.

C. Dai, P.C. Li, M. Toulouse, A Cooperative Multilevel Tabu Search Algorithm for the Covering Design Problem. LNCS 3871(2006), 119-130.

(Ben) Pak Ching Li and G.H. John van Rees. Lotto Designs (pages 529-536) in The CRC Handbook of Combinatorial Designs, 2^nd Edition(2006)

P.C. Li, D.R. Stinson, G.H.J. van Rees and R. Wei. On {123,124,134}-free Systems. Congressus Numerantium , V183 (2006) 161-174.

Documents in Preparation

Some results on Sperner partition systems. In preparation.

Combinatorial labelings of graphs. In preparation.

Negative results on consecutive antimagic labelings of graphs. In preparation.

Service Work

I am currently an associate head (from July 2009 to June 20112) and chair of the undergraduate curriculum committee in the department of Computer Science.

Other Stuff

A food blog.

A bursary that we set up for Joanne in the Department of Biosystems Engineering.

Contact Information

phone: (204) 474-8834
fax: (204) 474-7609
email: lipakc AT cs DOT umanitoba DOT ca

Last Updated: May 20, 2011