Yusuke Kobayashi gave an online talk on his algorithm for finding a large subgraph keeping the distance function differs by at most a constant at the Virtual Discrete Math Colloquium

On January 20, 2021, Yusuke Kobayashi (小林 佑輔) from RIMS, Kyoto University gave an online talk at the Virtual Discrete Math Colloquium on the fixed-parameter tractability of the problem of finding a small set X of edges such that for every pair v, w of vertices the distance from v to w in G is at most a constant plus the distance from v to w in G-X. The title of his talk was “An FPT Algorithm for Minimum Additive Spanner Problem“.

Rose McCarty presented a result on flooding immersions of Eulerian group-labelled graphs motivated by vertex-minors of graphs at the Virtual Discrete Math Colloquium

At the Virtual Discrete Math Colloquium on January 13, 2021, Rose McCarty from University of Waterloo gave a talk presenting her work with Jim Geelen and Paul Wollan on flooding immersions of Eulerian group-labelled graphs, related to vertex-minors of graphs. The title of her talk was “Vertex-minors and flooding immersions“.

O-joung Kwon (권오정) gave a talk on generalizing tangles and tangle-tree decompositions to directed graphs at the Discrete Math Seminar

On January 5, 2021, O-joung Kwon (권오정) from Incheon National University and IBS Discrete Mathematics Group presented his recent work with Archontia C. Giannopoulou, Ken-ichi Kawarabayashi, Stephan Kreutzer, and Qiqin Xie on generalizing tangles and tangle-tree decompositions to directed graphs at the Discrete Math Seminar. The title of his talk was “Directed tangles and applications“.

Paul Seymour gave an online talk on the recent result regarding the Erdős-Hajnal conjecture at the Virtual Discrete Math Colloquium

On December 30, 2020, Paul Seymour from Princeton University was the speaker of the Virtual Discrete Math Colloquium. He presented his recent breakthrough on the Erdős-Hajnal conjecture with Maria Chudnovsky, Alex Scott, and Sophie Spirkl, which in particular proves that the Erdős-Hajnal conjecture holds for the cycle of length 5. The title of his talk was “The Erdős-Hajnal conjecture is true for excluding a five-cycle“.

Jinha Kim explained the recent result on the Kalai-Meshulam conjecture by Zhang and Wu at the Discrete Math Seminar

On December 22, 2020, at the Discrete Math Seminar, Jinha Kim (김진하) from the IBS Discrete Mathematics Group presented the proof of the Kalai-Meshulam conjecture by Zhang and Wu, proving that for a graph G, the total Betti number of the independence complex of every induced subgraph of G is at most 1 if and only if G has no induced cycle of length 0 mod 3. The title of her talk was “On a conjecture by Kalai and Meshulam – the Betti number of the independence complex of ternary graphs“.