Marcelo Sales, On Pisier type problems
Zoom ID: 224 221 2686 (ibsecopro)A subset $A\subseteq \mathbb Z$ of integers is free if for every two distinct subsets $B, B'\subseteq A$ we have \Pisier asked if for every subset $A\subseteq \mathbb Z$ of …
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Seminars and Colloquiums
Stijn Cambie, Recent progress on the Union-closed conjecture and related
Room B332 IBS (기초과학연구원)We give a summary on the work of the last months related to Frankl's Union-Closed conjecture and its offsprings. The initial conjecture is stated as a theorem in extremal set …
Paul Seymour, A loglog step towards the Erdős-Hajnal conjecture
Zoom ID: 869 4632 6610 (ibsdimag)In 1977, Erdős and Hajnal made the conjecture that, for every graph $H$, there exists $c>0$ such that every $H$-free graph $G$ has a clique or stable set of size …
Younjin Kim (김연진), Problems on Extremal Combinatorics
Room B332 IBS (기초과학연구원)Extremal Combinatorics studies the maximum or minimum size of finite objects (numbers, sets, graphs) satisfying certain properties. In this talk, I introduce the conjectures I solved on Extremal Combinatorics, and …
Qizhong Lin, Two classical Ramsey-Turán numbers involving triangles
Zoom ID: 224 221 2686 (ibsecopro)In 1993, Erdős, Hajnal, Simonovits, Sós and Szemerédi proposed to determine the value of Ramsey-Turán density $\rho(3,q)$ for $q\ge3$. Erdős et al. (1993) and Kim, Kim and Liu (2019) proposed …
Tianchi Yang, On the maximum number of edges in k-critical graphs
Room B332 IBS (기초과학연구원)In this talk, we will discuss the problem of determining the maximum number of edges in an n-vertex k-critical graph. A graph is considered k-critical if its chromatic number is …
István Tomon, Configurations of boxes
Room B332 IBS (기초과학연구원)Configurations of axis-parallel boxes in $\mathbb{R}^d$ are extensively studied in combinatorial geometry. Despite their perceived simplicity, there are many problems involving their structure that are not well understood. I will …
Jie Han, Spanning trees in expanders
Zoom ID: 224 221 2686 (ibsecopro)We consider the spanning tree embedding problem in dense graphs without bipartite holes and sparse graphs. In 2005, Alon, Krivelevich and Sudakov asked for determining the best possible spectral gap …
James Davies, Two structural results for pivot-minors
Room B332 IBS (기초과학연구원)Pivot-minors can be thought of as a dense analogue of graph minors. We shall discuss pivot-minors and two recent results for proper pivot-minor-closed classes of graphs. In particular, that for …
Shin-ichiro Seki, On the extension of the Green-Tao theorem to number fields
Zoom ID: 897 6822 0619 (ibsecopro) [04/19 only]In 2006, Tao established the Gaussian counterpart of the celebrated Green-Tao theorem on arithmetic progressions of primes. In this talk, I will explain the extension of Tao's theorem and the …