Meike Hatzel, Constant congestion bramble
In this talk I will present a small result we achieved during a workshop in February this year. My coauthors on this are Marcin Pilipczuk, Paweł Komosa and Manuel Sorge. A …
10 events found.
Virtual Discrete Math Colloquium
Events
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Zoom ID: 869 4632 6610 (ibsdimag)
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Yijia Chen (陈翌佳), Graphs of bounded shrub-depth, through a logic lens
Zoom ID: 869 4632 6610 (ibsdimag)Shrub-depth is a graph invariant often considered as an extension of tree-depth to dense graphs. In this talk I will explain our recent proofs of two results about graphs of …
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Da Qi Chen, Bipartite Saturation
Zoom ID: 869 4632 6610 (ibsdimag)In extremal graph theory, a graph G is H-saturated if G does not contain a copy of H but adding any missing edge to G creates a copy of H. …
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Deniz Sarikaya, What means Hamiltonicity for infinite graphs and how to force it via forbidden induced subgraphs
Zoom ID: 869 4632 6610 (ibsdimag)The study of Hamiltonian graphs, i.e. finite graphs having a cycle that contains all vertices of the graph, is a central theme of finite graph theory. For infinite graphs such …
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Karl Heuer, Even Circuits in Oriented Matroids
Zoom ID: 869 4632 6610 (ibsdimag)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 …
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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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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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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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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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Dong Yeap Kang (강동엽), A proof of the Erdős-Faber-Lovász conjecture
Zoom ID: 869 4632 6610 (ibsdimag)A hypergraph is linear if every pair of two distinct edges shares at most one vertex. A longstanding conjecture by Erdős, Faber, and Lovász in 1972, states that the chromatic …