W.W. Tsang

W. W. TSANG

曾衛寰
W.W. Tsang B.Sc.(CUHK), M.S., Ph.D.(WSU)
Associate Professor

Teaching

Dr. Tsang had taught at the Washington State University (1982-83), the Arizona State University (1983-84) and the National University of Singapore (1984-87) before joining HKU. He enjoys teaching and has taught courses on programming, data structures, algorithms, theory of computing, numerical computing, computer networks, graphics, artificial intelligence, and discrete event simulation. This year he is teaching two courses, Computer Concepts and Programming (Java) and Introduction to Computer Graphics .

Research

Random number generation
Dr. Tsang has worked on random number generation with his Ph.D. supervisor, Prof. George Marsaglia, for more than 20 years. They have developed efficient methods for generate random variables in computers. Many of these methods are still the fastest and were cited in classic books, including the newer editions of Knuth's The Art of Computer Programming, and Kennedy and Gentles' Statistical Computing. Recently, he is investigating the power of tests for random number generators and studying methods for evaluating the CDF of the Kolmogorov's statistic.
Cryptography
Dr. Tsang is an active member of the Center for Information Security and Cryptography in the Engineering Faculty at HKU. The Centre is aimed at developing strong cryptographic infrastructure for users in Hong Kong. His involvement includes implementing a random number generation module and prototyping new cryptograhic methods.
Stringency scale for estimating the power of statistical tests against three families of random number generators
C functions that evaluate the CDFs of the Kolmogorov statistics when parameters are estimated from testing samples
A C program for the chi-square test when the expected frequencies are less than 5
A presentation on random number generation and testing, Dec. 2005

Publications in Statistical Computing

Xiaoke Xu and Wai Wan Tsang, An Empirical Study on the Power of the overlapping Serial Test, Proceedings of the Asia Simulation Conference 2007 (AsiaSim 2007), Seoul, Korea, October, 2007, 375-383.
Wai Wan Tsang and Kai Ho Cheng, The chi-square test when the expected frequencies are less than 5, Proceedings of the COMPSTAT 2006, 17th Symposium of IASC, Rome, August 28-September 1, 2006, 1583-1589.
Wai Wan Tsang and Chi-yin Pang, The mathematics of the overlapping chi-Square test, Technical Report: TR-2006-12, Department of Computer Science, The University of Hong Kong, September 2006. (available at http://www.cs.hku.hk/research/techreps/document/TR-2006-12.pdf).
Wai Wan Tsang and Jingbo Wang, Evaluating the CDF of the Kolmogorov statistic for normality testing, Proceedings of the COMPSTAT 2004, 16th Symposium of IASC, Prague, August 23-27, 2004, 1893-1900.
George Marsaglia, Wai Wan Tsang and Jingbo Wang, Fast Generation of Discrete Random Variables, Journal of Statistical Software, (available at http://www.jstatsoft.org/ ), Volume 11, Issue 3, July, 2004.
W.W. Tsang, L.C.K. Hui, K.P. Chow, C.F. Chong, and C.W. Tso, Tuning the collision test for power, Conferences in Research and Practice in Information Series, Vol. 26. No. 1, pp. 23-30, 2004. (Proceedings of the 27th Australasian Computer Science Conference, Dunedin, New Zealand, 2004.) (C program of two collision tests.)
G. Marsaglia and W.W. Tsang, The 64-bit universal RNG, Statistics & Probability Letters, Vol. 6, Issue 2, pp. 183-187, January, 2004.
G. Marsaglia, W.W. Tsang and J. Wang, Evaluating Kolmogorov's distribution, Journal of Statistical Software, (available at http://www.jstatsoft.org/ ), Vol. 8, Issue 18, Pages 1-4, November, 2003.
G. Marsaglia and W.W. Tsang, Some difficult-to-pass tests of randomness, Journal of Statistical Software, (available at http://www.jstatsoft.org/ ), Vol. 7, Issue 3, Pages 1-8, January, 2002.
G. Marsaglia and W.W. Tsang, The ziggurat method for generating random variables, Journal of Statistical Software, (available at http://www.jstatsoft.org/ ), Vol. 5, Issue 8, Pages 1-7, October, 2000.
G. Marsaglia and W.W. Tsang, A simple method for generating gamma variables, ACM Transactions on Mathematical Software, Vol. 26, No. 3, Pages 363-372, September, 2000.
G. Marsaglia and W.W. Tsang, The Monty Python method for generating gamma variables, Journal of Statistical Software (available at http://www.jstatsoft.org/ ), Vol. 3, Issue 3, Pages 1-8, January 1999.
G. Marsaglia and W.W. Tsang, The Monty Python method for generating random variables, ACM Transactions on Mathematical Software, Vol. 24, No. 3, Pages 341-350, September, 1998.
G. Marsaglia, A. Zaman and W.W. Tsang, Toward a universal random number generator, Statistics & Probability Letters, 9 (1), 35-39, January 1990.
W.W. Tsang and G. Marsaglia, A decision tree algorithm for squaring histograms in random number generation, ARS Combinatoria, Vol. 23A, May 1987.
G. Marsaglia and W.W. Tsang, A fast, easily implemented method for sampling from decreasing or symmetric unimodal density functions, SIAM J. Sci. Stat. Comput., Vol. 5, No. 2, June 1984.

Selected Publications in Other Areas

Zichen Li, C. F. Chong, Lucas Chi Kwong Hui, Siu-Ming Yiu, K. P. Chow, Wai Wan Tsang, H. W. Chan, Kevin K. H. Pun, An Attack on Libert et al.' s ID-based Undeniable Signature Scheme. I. J. Network Security, September 2007: 220~223.
E.Y.K. Chan, H.W. Chan, K.M. Chan, P.S. Chan, S.T. Chanson, M.H. Cheung, C.F. Chong, K.P. Chow, A.K.T. Hui, L.C.K. Hui, S.K. Ip, C.K. Lam, W.C. Lau, K.H. Pun, Y.F. Tsang, W.W. Tsang, C.W. Tso, D.Y. Yeung, S.M. Yiu, K.Y. Yu, W. Ju, Intrusion Detection Routers: Design, Implementation and Evaluation Using an Experimental Test-bed, The IEEE Journal on Selected Areas in Communications, special issue on High-speed Network Security, October 2006, 1889-1900.
Henry C.M. Leung, Francis Y.L. Chin, S.M. Yiu, Roni Rosenfeld, W.W. Tsang, finding Motifs with Insufficient Number of Strong Binding Sites, Journal of Computational Biology, 12(6), 686-701 (July 2005).
Q. Ding, J. Qian, W. W. Tsang and C. Wang, Randomly Generating Triangulations of a Simple Polygon, Lecture Notes in Computer Science (LNCS) 3595, Computing and Combinatorics , L. Wang (Ed.), 471-480, Springer-Verlag 2005. (Proceedings of the 11th Annual International Computing and Combinatorics Conference (COCOON), Kunming, China, August 2005.)
Eric Y.K. Chan, H.W. Chan, K.M. Chan, Vivien P.S. Chan, Samuel T. Chanson, Matthew M.H. Cheung, C.F. Chong, K.P. Chow, Albert K.T. Hui, Lucas C.K. Hui, Luke C.K. Lam, W.C. Lau, Kevin K.H. Pun, Anthony Y.F. Tsang, W.W. Tsang, Sam C.W. Tso, Dit-Yan Yeung, K.Y. Yu, IDR: An Intrusion Detection Router for Defending against Distributed Denial-of-Service (DDoS) Attacks, Proceedings of the Seventh International Symposium on Parallel Architectures, Algorithms and Networks, Hong Kong SAR, May 2004, 581-586.
Francis Y.L. Chin, Henry C.M. Leung, S.M. Yiu, T.W. Lam, Roni Rosenfeld, W.W. Tsang, David K. Smith, Y.Jiang, Finding Motifs for Insufficient Number of Sequences with Strong Binding to Transcription Factor, Proceedings of the Eighth Annual International Conference on Research in Computational Molecular Biology (RECOMB 2004), San Deigo, March 2004.
K.H. Pun, Lucas Hui, K.P. Chow, W.W. Tsang, C.F. Chong and H.W. Chan, Review of the Electronic Transactions Ordinance: Can the Personal Identification Number Replace the Digital Signature, Hong Kong Law Journal, Vol. 22, Part 2, 2002.
L.C.K. Hui, K.P. Chow, W.W. Tsang, C.F. Chong, H.W. Chan, V. Chan, K.M. Chan, M. Lee, D. Hung, C.T. Hung, P. Hong, P. Yeung, Strong Cryptographic Library - Implementation and Applications, Proceedings of the 9th Hong Kong Computer Society Data Base Conference, Pages 107-112, Hong Kong, May 1999.
X. Tong, W. Wang, W.W. Tsang and Z. Tang, Efficiently rendering large volume data using texture mapping hardware, Proceeding of the Joint EUROGRAPHICS - IEEE TCCG Symposium on Visualization 1999 (VisSym '99), Vienna, Austria, May 1999.
K.W. Wong and W.W. Tsang, An efficient shadow algorithm for area light sources using BSP trees, Proceedings of Pacific Graphics 98, Pages 97-102, Singapore, October, 1998.
F. Ma, W. Wang, W.W. Tsang, Z. Tang, S. Xia and X. Tong, Probabilistic segmentation of volume data for visualization using SOM-PNN classifier, Proceedings of the 1998 Symposium on Volume Visualization, Pages 71-77, Research Triangle Park, North Carolina, USA, October, 1998.
K.W. Wong and W.W. Tsang, Visualization of errors on form-factor computation, Transactions of the Hong Kong Institution of Engineers, Vol. 1, No. 1, August 1994.
N.V. Findler, T.W. Bickmore, L.H. Ihrig and W.W. Tsang, A note on the comparison of five heuristic optimization techniques of a certain class of decision trees, Information Sciences, 53. 1991.
W.W. Tsang, T.W. Lam and F. Chin, An optimal EREW algorithm for parenthesis matching, Proceedings of the 18th Annual International Conference on Parallel Processing, St. Charles, August 1989.
F. Chin, W.W. Tsang, and T.W. Lam, Efficient parallel algorithms for some subsequence problems, Proceedings of the First Annual IEEE Symposium on Parallel and Distributed Processing, Dallas, May 1989.
W.W. Tsang, N.V. Findler and L.H. Ihrig, A pruning algorithm for finding optimal decision diagrams, Proceedings of International Conference on Optimization: Techniques & Applications, Singapore, April 1987.
H.H. Teh, L.S. Hsu and W.W. Tsang, Modeling knowledge information systems using inference nets, ARS Combinatoria, Vol. 23A, May 1987.

Last updated: January, 2011