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题目：Suitable sets of permutations, packings of triples, and Ramsey’s theorem
摘要：A set of N permutations of {1, 2,..., v} is t-suitable, if each symbol precedes each subset of
t-1 others in at least one permutation. The extremal problem of determining the smallest size N of such sets for given v and t was the subject of classical studies by Dushnik in 1950 and Spencer in 1971. In this talk, we discuss recent progress on this problem, by connecting with packings designs and Ramsey coloring.
报告人简介：张先得，中国科学技术大学研究员，从事组合数学和信息交叉学科研究。解决了设计理论中若干经典问题，推进了长达半个世纪的Ryser-Brualdi猜想，解决了编码密码学中若干最优码类的构造问题。发表SCI期刊论文30余篇，被国际组合及其应用协会授予Kirkman奖，任期刊《Journal of Combinatorial Designs》编委。
时间：2019年9月28日3:30-4:30
地点：长清校区B532报告厅
邀请人：张霞
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