Nicola Lorenz, A Minor Characterisation of Normally Spanned Sets of Vertices
A rooted spanning tree of a graph $G$ is called normal if the endvertices of all edges of $G$ are comparable in the tree order. It is well known that …
10 events found.
Discrete Math Seminar
Events
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Room B332 IBS (기초과학연구원)
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Marcin Briański, Burling Graphs as (almost) universal obstacles to $\chi$-boundedness
Room B332 IBS (기초과학연구원)What causes a graph to have high chromatic number? One obvious reason is containing a large clique (a set of pairwise adjacent vertices). This naturally leads to investigation of \(\chi\)-bounded …
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Pascal Schweitzer, Recent insights surrounding combinatorial approaches to isomorphism and symmetry problems
Room B332 IBS (기초과학연구원)Modern practical software libraries that are designed for isomorphism tests and symmetry computation rely on combinatorial techniques combined with techniques from algorithmic group theory. The Weisfeiler-Leman algorithm is such a …
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Eunjin Oh (오은진), Approximation Algorithms for the Geometric Multimatching Problem
Room B332 IBS (기초과학연구원)Let S and T be two sets of points in a metric space with a total of n points. Each point in S and T has an associated value that specifies an upper limit on how many points it can …
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Seokbeom Kim (김석범), The structure of △(1, 2, 2)-free tournaments
Room B332 IBS (기초과학연구원)Given a tournament $S$, a tournament is $S$-free if it has no subtournament isomorphic to $S$. Until now, there have been only a small number of tournaments $S$ such that …
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Meike Hatzel, Counterexample to Babai’s lonely colour conjecture
Room B332 IBS (기초과학연구원)Motivated by colouring minimal Cayley graphs, in 1978 Babai conjectured that no-lonely-colour graphs have bounded chromatic number. We disprove this in a strong sense by constructing graphs of arbitrarily large …
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Denys Bulavka, Strict Erdős-Ko-Rado Theorems for Simplicial Complexes
Room B332 IBS (기초과학연구원)The now classical theorem of Erdős, Ko and Rado establishes the size of a maximal uniform family of pairwise-intersecting sets as well as a characterization of the families attaining such …
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On-Hei Solomon Lo, Minors of non-hamiltonian graphs
Room B332 IBS (기초과학연구원)A seminal result of Tutte asserts that every 4-connected planar graph is hamiltonian. By Wagner's theorem, Tutte's result can be restated as: every 4-connected graph with no $K_{3,3}$ minor is …
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Attila Jung, The Quantitative Fractional Helly Theorem
Room B332 IBS (기초과학연구원)Two celebrated extensions of Helly's theorem are the Fractional Helly theorem of Katchalski and Liu (1979) and the Quantitative Volume theorem of Barany, Katchalski, and Pach (1982). Improving on several …
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Roohani Sharma, Uniform and Constructive Polynomial Kernel for Deletion to $K_{2,p}$ Minor-Free Graphs
Room B332 IBS (기초과학연구원)Let $\mathcal F$ be a fixed, finite family of graphs. In the $\mathcal F$-Deletion problem, the input is a graph G and a positive integer k, and the goal is …