Jaehyeon Seo (서재현), A rainbow Turán problem for color-critical graphs
For given $k$ graphs $G_1,\dots, G_k$ over a common vertex set of size $n$, what conditions on $G_i$ ensures a 'colorful' copy of $H$, i.e. a copy of $H$ containing …
10 events found.
Discrete Math Seminar
Events
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Room B232 IBS (기초과학연구원)
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O-joung Kwon (권오정), Reduced bandwidth: a qualitative strengthening of twin-width in minor-closed classes (and beyond)
Room B232 IBS (기초과학연구원)In a reduction sequence of a graph, vertices are successively identified until the graph has one vertex. At each step, when identifying $u$ and $v$, each edge incident to exactly …
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Pascal Gollin, A unified Erdős-Pósa theorem for cycles in graphs labelled by multiple abelian groups
Room B232 IBS (기초과학연구원)Erdős and Pósa proved in 1965 that there is a duality between the maximum size of a packing of cycles and the minimum size of a vertex set hitting all …
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Jinha Kim (김진하), Independent domination of graphs with bounded maximum degree
Room B232 IBS (기초과학연구원)An independent dominating set of a graph, also known as a maximal independent set, is a set $S$ of pairwise non-adjacent vertices such that every vertex not in $S$ is …
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Donggyu Kim (김동규), A stronger version of Tutte’s wheel theorem for vertex-minors
Room B232 IBS (기초과학연구원)Tutte (1961) proved that every simple $3$-connected graph $G$ has an edge $e$ such that $G \setminus e$ or $G / e$ is simple $3$-connected, unless $G$ is isomorphic to …
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Sang-il Oum (엄상일), Obstructions for matroids of path-width at most k and graphs of linear rank-width at most k
Room B232 IBS (기초과학연구원)Every minor-closed class of matroids of bounded branch-width can be characterized by a minimal list of excluded minors, but unlike graphs, this list could be infinite in general. However, for …
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Kevin Hendrey, A unified Erdős-Pósa theorem for cycles in graphs labelled by multiple abelian groups (revisited)
Room B232 IBS (기초과학연구원)This talk follows on from the recent talk of Pascal Gollin in this seminar series, but will aim to be accessible for newcomers. Erdős and Pósa proved in 1965 that …
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Tuan Anh Do, Rank- and tree-width of supercritical random graphs
Room B232 IBS (기초과학연구원)It is known that the rank- and tree-width of the random graph $G(n,p)$ undergo a phase transition at $p = 1/n$; whilst for subcritical $p$, the rank- and tree-width are bounded above …
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Jaehoon Kim (김재훈), Ramsey numbers of cycles versus general graphs
Room B232 IBS (기초과학연구원)The Ramsey number $R(F,H)$ is the minimum number $N$ such that any $N$-vertex graph either contains a copy of $F$ or its complement contains $H$. Burr in 1981 proved a …
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Ben Lund, Thresholds for incidence properties in finite vector spaces
Room B232 IBS (기초과학연구원)Suppose that $E$ is a subset of $\mathbb{F}_q^n$, so that each point is contained in $E$ with probability $\theta$, independently of all other points. Then, what is the probability that …