Rutger Campbell, Disasters in abstracting combinatorial properties of linear dependence

Room B232 IBS (기초과학연구원)

Let E be a finite set and I be a collection of subsets of E. When is there a set of real vectors indexed by E such that I correspond to its linearly independent subsets? In 1935, Whitney introduced matroids using some necessary conditions for this. However, complete characterizations with various techniques are intractable. This remains the case even if it is already known

Sebastian Siebertz, Rank-width meets stability

Zoom ID: 869 4632 6610 (ibsdimag)

Forbidden graph characterizations provide a convenient way of specifying graph classes, which often exhibit a rich combinatorial and algorithmic theory. A prime example in graph theory are classes of bounded tree-width, which are characterized as those classes that exclude some planar graph as a minor. Similarly, in model theory, classes of structures are characterized by

Debsoumya Chakraborti, Maximum number of cliques in a graph with bounded maximum degree

Room B232 IBS (기초과학연구원)

Generalized extremal problems have been one of the central topics of study in extremal combinatorics throughout the last few decades. One such simple-looking problem, maximizing the number of cliques of a fixed order in a graph with a fixed number of vertices and given maximum degree, was recently resolved by Chase. Settling a conjecture of

Luke Postle, Further progress towards Hadwiger’s conjecture

Zoom ID: 869 4632 6610 (ibsdimag)

In 1943, Hadwiger conjectured that every graph with no $K_t$ minor is $(t-1)$-colorable for every $t\ge 1$. In the 1980s, Kostochka and Thomason independently proved that every graph with no $K_t$ minor has average degree $O(t\sqrt{\log t})$ and hence is $O(t\sqrt{\log t})$-colorable.  Recently, Norin, Song and I showed that every graph with no $K_t$ minor is

Zihan Tan, Towards Tight(er) Bounds for the Excluded Grid Theorem

Zoom ID: 869 4632 6610 (ibsdimag)

We study the Excluded Grid Theorem, a fundamental structural result in graph theory, that was proved by Robertson and Seymour in their seminal work on graph minors. The theorem states that there is a function $f$, such that for every integer $g > 0$, every graph of treewidth at least $f(g)$ contains the g×g-grid as a minor. For every

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 an independent set of size $n$ in $G$. We study the collapsibility numbers of $I_n(G)$ for various classes of graphs, focusing on the class of

Livestream

Hong Liu (刘鸿), Cycles and trees in graphs (1/8)

Zoom ID:8628398170 (123450)

This lecture series covers several different techniques on embedding paths/trees/cycles in (pseudo)random graphs/expanders as (induced) subgraphs.

Livestream

Hong Liu (刘鸿), Cycles and trees in graphs (2/8)

Zoom ID:8628398170 (123450)

This lecture series covers several different techniques on embedding paths/trees/cycles in (pseudo)random graphs/expanders as (induced) subgraphs.

Livestream

Hong Liu (刘鸿), Cycles and trees in graphs (3/8)

Zoom ID:8628398170 (123450)

This lecture series covers several different techniques on embedding paths/trees/cycles in (pseudo)random graphs/expanders as (induced) subgraphs.

IBS 이산수학그룹 Discrete Mathematics Group
기초과학연구원 수리및계산과학연구단 이산수학그룹
대전 유성구 엑스포로 55 (우) 34126
IBS Discrete Mathematics Group (DIMAG)
Institute for Basic Science (IBS)
55 Expo-ro Yuseong-gu Daejeon 34126 South Korea
E-mail: dimag@ibs.re.kr, Fax: +82-42-878-9209
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