Marcelo Garlet Milani, Cycles of Well-Linked Sets and an Elementary Bound for the Directed Grid Theorem

Room B332 IBS (기초과학연구원)

In 2015, Kawarabayashi and Kreutzer proved the directed grid theorem. The theorem states the existence of a function f such that every digraph of directed tree-width f(k) contains a cylindrical grid of order k as a butterfly minor, but the given function grows non-elementarily with the size of the grid minor. We present an alternative

Daniel McGinnis, A necessary and sufficient condition for k-transversals

Room B332 IBS (기초과학연구원)

We solve a long-standing open problem posed by Goodman and Pollack in 1988 by establishing a necessary and sufficient condition for a finite family of convex sets in Rd to admit a k-transversal (a k-dimensional affine subspace that intersects each set) for any 0kd1. This result is a common generalization of

Nicola Lorenz, A Minor Characterisation of Normally Spanned Sets of Vertices

Room B332 IBS (기초과학연구원)

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 every finite connected graph has a normal spanning tree (also known as depth-first search tree). Also, all countable graphs have normal spanning trees, but uncountable

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 be matched with from the other set. A multimatching between S and T is a way of pairing points such that each point in S is matched with at least as many

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 the complete structure of S-free tournaments is known. Let (1,2,2) be a tournament obtained from the cyclic triangle by substituting two-vertex tournaments for

Sergey Norin, TBA

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IBS 이산수학그룹 Discrete Mathematics Group
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