2021 Combinatorics Workshop (2021 조합론 학술대회)
The Combinatorics Workshop (조합론 학술대회) is an annual conference of combinatorialists in Korea that started in 2004 by the Yonsei University BK21 Research Group. Since 2013, this workshop has been …
10 events found.
Events
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The Bloomvista
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Seunghun Lee (이승훈), Transversals and colorings of simplicial spheres
Room B232 IBS (기초과학연구원)Motivated from the surrounding property of a point set in $\mathbb{R}^d$ introduced by Holmsen, Pach and Tverberg, we consider the transversal number and chromatic number of a simplicial sphere. As …
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Andreas Holmsen, Some recent results on geometric transversals
Room B232 IBS (기초과학연구원)A geometric transversal to a family of convex sets in $\mathbb R^d$ is an affine flat that intersects the members of the family. While there exists a far-reaching theory concerning …
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Ron Aharoni, A strong version of the Caccetta-Haggkvist conjecture
Zoom ID: 869 4632 6610 (ibsdimag)The Caccetta-Haggkvist conjecture, one of the best known in graph theory, is that in a digraph with $n$ vertices in which all outdegrees are at least $n/k$ there is a …
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Jaehyeon Seo (서재현), A rainbow Turán problem for color-critical graphs
Room B232 IBS (기초과학연구원)For given $k$ graphs $G_1,\dots, G_k$ over a common vertex set of size $n$, what conditions on $G_i$ ensures a 'colorful' copy of $H$, i.e. a copy of $H$ containing …
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Ken-ichi Kawarabayashi (河原林 健一), Toward Directed Graph Minor Theory
Zoom ID: 869 4632 6610 (ibsdimag)Graph Minor project by Robertson and Seymour is perhaps the deepest theory in Graph Theory. It gives a deep structural characterization of graphs without any graph $H$ as a minor. …
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O-joung Kwon (권오정), Reduced bandwidth: a qualitative strengthening of twin-width in minor-closed classes (and beyond)
Room B232 IBS (기초과학연구원)In a reduction sequence of a graph, vertices are successively identified until the graph has one vertex. At each step, when identifying $u$ and $v$, each edge incident to exactly …
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Bo Ning (宁博), Substructures and eigenvalues of graphs: Triangles and quadrilaterals
Zoom ID: 869 4632 6610 (ibsdimag)Our talk will mainly focus on the relationship between substructures and eigenvalues of graphs. We will briefly survey recent developments on a conjecture of Bollobás and Nikiforov and a classical …
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Pascal Gollin, A unified Erdős-Pósa theorem for cycles in graphs labelled by multiple abelian groups
Room B232 IBS (기초과학연구원)Erdős and Pósa proved in 1965 that there is a duality between the maximum size of a packing of cycles and the minimum size of a vertex set hitting all …
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James Davies, Separating polynomial $\chi$-boundedness from $\chi$-boundedness
Zoom ID: 869 4632 6610 (ibsdimag)We prove that there is a function $f : \mathbb{N} \to \mathbb{N}$ such that for every function $g : \mathbb{N} \to \mathbb{N} \cup \{\infty\}$ with $g(1)=1$ and $g \ge f$, …