报告题目：Big Ramsey degrees of universal structures
报告人：Jan Hubička Charles University
报告时间：2025年6月27日（周五）15：00 - 16:00
报告地点：20-306
报告摘要：A structure M is said to have finite big Ramsey degrees if for any of its finite substructures A, there exists a number BRD(M,A) such that for any finite coloring of the copies of A within M, one can find a copy of M in M that uses at most BRD(A,M) colors. Denoting by N the set of all integers seen as an linearly ordered set, by the classical infinite Ramsey theorem, for every finite order O it holds that BRD(O,N)=1. The study of big Ramsey degrees was initiated in 1960's by results of Sierpinski, Galvin, Devlin and Laver on coloring suborders of the order of rationals. Recently the area has been revitalized with number of new results. In this talk I will introduce the main concepts and dicuss a new proof technique which can be used to show that every countable universal triangle-free graph has finite big Ramsey degree.
报告人简介：Jan Hubička博士是捷克查理大学应用数学系副教授，同时也是 SUSE 软件公司的开发者。他的研究方向包括结构 Ramsey 理论、图同态以及齐性结构等。他在 Proc. Lond. Math. Soc.、Adv. Math.、Trans. Amer. Math. Soc.、Combinatorica、J. Combin. Theory Ser. B、J. Combin. Theory Ser. A、Adv. Comb. 等期刊发表论文30余篇。 此外，Jan 博士是 GNU 编译器集合（GCC）项目的长期贡献者，曾实现对 x86-64 架构的初始移植工作，并维护跨过程优化、基于反馈的优化以及 i386 架构的支持。他也对摄影史有浓厚兴趣，致力于 Šechtl 与 Voseček 工作室历史影像档案的数字化工作。
邀请人：朱绪鼎