Hong Liu (刘鸿), Nested cycles with no geometric crossing
In 1975, Erdős asked the following question: what is the smallest function $f(n)$ for which all graphs with $n$ vertices and $f(n)$ edges contain two edge-disjoint cycles $C_1$ and $C_2$, …
10 events found.
Discrete Math Seminar
Events
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Room B232 IBS (기초과학연구원)
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Casey Tompkins, 3-uniform hypergraphs avoiding a cycle of length four
Room B232 IBS (기초과학연구원)We show that that the maximum number of of edges in a $3$-uniform hypergraph without a Berge-cycle of length four is at most $(1+o(1)) \frac{n^{3/2}}{\sqrt{10}}$. This improves earlier estimates by …
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Rutger Campbell, Matroid orientability and representability
Room B232 IBS (기초과학연구원)In this talk we will have a brief introduction to oriented matroids and their relation to real-representability.
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William Overman, Some Ordered Ramsey Numbers of Graphs on Four Vertices
Room B232 IBS (기초과학연구원)Ordered Ramsey numbers were introduced in 2014 by Conlon, Fox, Lee, and Sudakov. Their results included upper bounds for general graphs and lower bounds showing separation from classical Ramsey numbers. We …
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Sang-il Oum (엄상일), What is an isotropic system?
Room B232 IBS (기초과학연구원)Bouchet introduced isotropic systems in 1983 unifying some combinatorial features of binary matroids and 4-regular graphs. The concept of isotropic system is a useful tool to study vertex-minors of graphs …
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Jungho Ahn (안정호), Well-partitioned chordal graphs with the obstruction set and applications
Room B232 IBS (기초과학연구원)We introduce a new subclass of chordal graphs that generalizes split graphs, which we call well-partitioned chordal graphs. Split graphs are graphs that admit a partition of the vertex set …
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Mark Siggers, The list switch homomorphism problem for signed graphs
Room B232 IBS (기초과학연구원)A signed graph is a graph in which each edge has a positive or negative sign. Calling two graphs switch equivalent if one can get from one to the other …
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Pascal Gollin, Enlarging vertex-flames in countable digraphs
Room B232 IBS (기초과학연구원)A rooted digraph is a vertex-flame if for every vertex v there is a set of internally disjoint directed paths from the root to v whose set of terminal edges covers all …
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Ben Lund, Limit shape of lattice Zonotopes
Room B232 IBS (기초과학연구원)A convex lattice polytope is the convex hull of a set of integral points. Vershik conjectured the existence of a limit shape for random convex lattice polygons, and three proofs …
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Doowon Koh (고두원), Mattila-Sjölin type functions: A finite field model
Room B232 IBS (기초과학연구원)Let $\mathbb{F}_q$ be a finite field of order $q$ which is a prime power. In the finite field setting, we say that a function $\phi\colon \mathbb{F}_q^d\times \mathbb{F}_q^d\to \mathbb{F}_q$ is a Mattila-Sjölin …