Karl Heuer, Even Circuits in Oriented Matroids
In this talk I will state a generalisation of the even directed cycle problem, which asks whether a given digraph contains a directed cycle of even length, to orientations of …
10 events found.
Seminars and Colloquiums
Events
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Zoom ID: 869 4632 6610 (ibsdimag)
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Jaiung Jun (전재웅), On the Hopf algebra of multi-complexes
Zoom ID: 869 4632 6610 (ibsdimag)In combinatorics, Hopf algebras appear naturally when studying various classes of combinatorial objects, such as graphs, matroids, posets or symmetric functions. Given such a class of combinatorial objects, basic information …
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Jinha Kim (김진하), On a conjecture by Kalai and Meshulam – the Betti number of the independence complex of ternary graphs
Room B232 IBS (기초과학연구원)Given a graph G=(V,E), the independence complex of G is the abstract simplicial complex I(G) on V whose faces are the independent sets of G. A graph is ternary if it does …
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Paul Seymour, The Erdős-Hajnal conjecture is true for excluding a five-cycle
Zoom ID: 869 4632 6610 (ibsdimag)In an n-vertex graph, there must be a clique or stable set of size at least $C\log n$, and there are graphs where this bound is attained. But if we look at …
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O-joung Kwon (권오정), Directed tangles and applications
Room B232 IBS (기초과학연구원)The canonical tree-decomposition theorem, proved by Robertson and Seymour in their seminal graph minors series, turns out to be an extremely valuable tool in structural and algorithmic graph theory. In …
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Andreas Holmsen, Discrete geometry in convexity spaces
Room B232 IBS (기초과학연구원)The notion of convexity spaces provides a purely combinatorial framework for certain problems in discrete geometry. In the last ten years, we have seen some progress on several open problems …
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Rose McCarty, Vertex-minors and flooding immersions
Zoom ID: 869 4632 6610 (ibsdimag)An immersion of a graph H into a graph G sends edges of H into edge-disjoint trails of G. We say the immersion is flooding if every edge of G …
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Ben Lund, Perfect matchings and derangements on graphs
Room B232 IBS (기초과학연구원)We show that each perfect matching in a bipartite graph G intersects at least half of the perfect matchings in G. This result has equivalent formulations in terms of the permanent …
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Yusuke Kobayashi (小林 佑輔), An FPT Algorithm for Minimum Additive Spanner Problem
Zoom ID: 869 4632 6610 (ibsdimag)For a positive integer t and a graph G, an additive t-spanner of G is a spanning subgraph in which the distance between every pair of vertices is at most …
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Tuan Tran, Minimum saturated families of sets
Room B232 IBS (기초과학연구원)A family $\mathcal F$ of subsets of is called s-saturated if it contains no s pairwise disjoint sets, and moreover, no set can be added to $\mathcal F$ while preserving …