Seminars and Colloquiums

Name: Jaiung Jun (전재웅), The Hall algebra of the category of matroids
Start: 2019-12-26T16:30:00+09:00
End: 2019-12-26T17:30:00+09:00
Location: Room 1401, Bldg. E6-1, KAIST

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0 events 8 0 events, 8	0 events 9 0 events, 9	1 event 10 1 event, 10 4:30 PM - 5:30 PM Jakub Gajarský, First-order interpretations of bounded expansion classes Tuesday, December 10, 2019 @ 4:30 PM - 5:30 PM KST Jakub Gajarský, First-order interpretations of bounded expansion classes The notion of bounded expansion captures uniform sparsity of graph classes and renders various algorithmic problems that are hard in general tractable. In particular, the model-checking problem for first-order logic is fixed-parameter tractable over such graph classes. With the aim of generalizing such results to dense graphs, we introduce classes of graphs with structurally bounded expansion, defined as first-order interpretations of … Continue Reading	0 events 11 0 events, 11	1 event 12 1 event, 12 4:30 PM - 5:30 PM Hong Liu, A proof of Mader’s conjecture on large clique subdivisions in $C_4$-free graphs Thursday, December 12, 2019 @ 4:30 PM - 5:30 PM KST Hong Liu, A proof of Mader’s conjecture on large clique subdivisions in $C_4$-free graphs Given any integers $s,t\geq 2$, we show there exists some $c=c(s,t)>0$ such that any $K_{s,t}$-free graph with average degree $d$ contains a subdivision of a clique with at least $cd^{\frac{1}{2}\frac{s}{s-1}}$ vertices. In particular, when $s=2$ this resolves in a strong sense the conjecture of Mader in 1999 that every $C_4$-free graph has a subdivision of … Continue Reading	0 events 13 0 events, 13	0 events 14 0 events, 14
0 events 15 0 events, 15	0 events 16 0 events, 16	0 events 17 0 events, 17	0 events 18 0 events, 18	1 event 19 1 event, 19 4:30 PM - 5:30 PM Attila Joó, Base partition for finitary-cofinitary matroid families Thursday, December 19, 2019 @ 4:30 PM - 5:30 PM KST Attila Joó, Base partition for finitary-cofinitary matroid families Let ${\mathcal{M} = (M_i \colon i\in K)}$ be a finite or infinite family consisting of finitary and cofinitary matroids on a common ground set $E$. We prove the following Cantor-Bernstein-type result: if $E$ can be covered by sets ${(B_i \colon i\in K)}$ which are bases in the corresponding matroids and there are also pairwise disjoint … Continue Reading	0 events 20 0 events, 20	0 events 21 0 events, 21
0 events 22 0 events, 22	0 events 23 0 events, 23	0 events 24 0 events, 24	0 events 25 0 events, 25	1 event 26 1 event, 26 4:30 PM - 5:30 PM Jaiung Jun (전재웅), The Hall algebra of the category of matroids Thursday, December 26, 2019 @ 4:30 PM - 5:30 PM KST Jaiung Jun (전재웅), The Hall algebra of the category of matroids To an abelian category A satisfying certain finiteness conditions, one can associate an algebra H_A (the Hall algebra of A) which encodes the structures of the space of extensions between objects in A. For a non-additive setting, Dyckerhoff and Kapranov introduced the notion of proto-exact categories, as a non-additive generalization of an exact category, which … Continue Reading	0 events 27 0 events, 27	0 events 28 0 events, 28
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