Jinha Kim (김진하), Collapsibility of Non-Cover Complexes of Graphs
Room B232 IBS (기초과학연구원)Let $G$ be a graph on the vertex set $V$. A vertex subset $W \subset V$ is a cover of $G$ if $V \setminus W$ is an independent set of …
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Discrete Math Seminar
Minki Kim (김민기), Complexes of graphs with bounded independence number
Room B232 IBS (기초과학연구원)Let $G$ be a graph on $V$ and $n$ a positive integer. Let $I_n(G)$ be the abstract simplicial complex whose faces are the subsets of $V$ that do not contain …
Joonkyung Lee (이준경), On graph norms for complex-valued functions
Room B232 IBS (기초과학연구원)For any given graph $H$, one may define a natural corresponding functional $\|.\|_H$ for real-valued functions by using homomorphism density. One may also extend this to complex-valued functions, once $H$ …
Jeong Ok Choi (최정옥), Various game-theoretic models on graphs
Room B232 IBS (기초과학연구원)We introduce some of well-known game-theoretic graph models and related problems. A contagion game model explains how an innovation diffuses over a given network structure and focuses on finding conditions …
Jaeseong Oh (오재성), A 2-isomorphism theorem for delta-matroids
Room B232 IBS (기초과학연구원)Whitney’s 2-Isomorphism Theorem characterises when two graphs have isomorphic cycle matroids. In this talk, we present an analogue of this theorem for graphs embedded in surfaces by characterising when two …
Casey Tompkins, Extremal forbidden poset problems in Boolean and linear lattices
Room B232 IBS (기초과학연구원)Extending the classical theorem of Sperner on the maximum size of an antichain in the Boolean lattice, Katona and Tarján introduced a general extremal function $La(n,P)$, defined to be the …
Duksang Lee (이덕상), Characterizing matroids whose bases form graphic delta-matroids
Room B232 IBS (기초과학연구원)We introduce delta-graphic matroids, which are matroids whose bases form graphic delta-matroids. The class of delta-graphic matroids contains graphic matroids as well as cographic matroids and is a proper subclass …
Joonkyung Lee (이준경), On Ramsey multiplicity
Zoom ID:8628398170 (123450)Ramsey's theorem states that, for a fixed graph $H$, every 2-edge-colouring of $K_n$ contains a monochromatic copy of $H$ whenever $n$ is large enough. Perhaps one of the most natural …
Debsoumya Chakraborti, Rainbow matchings in edge-colored simple graphs
Room B232 IBS (기초과학연구원)There has been much research on finding a large rainbow matching in a properly edge-colored graph, where a proper edge coloring is a coloring of the edge set such that …
Joonkyung Lee (이준경), On common graphs
Zoom ID:8628398170 (123450)A graph $H$ is common if the number of monochromatic copies of $H$ in a 2-edge-colouring of the complete graph $K_n$ is minimised by the random colouring. Burr and Rosta, extending …