István Tomon, Ramsey properties of semilinear graphs
Zoom ID: 869 4632 6610 (ibsdimag)A graph
10 events found.
Sang-il Oum (엄상일), What is an isotropic system?
Room B232 IBS (기초과학연구원)Bouchet introduced isotropic systems in 1983 unifying some combinatorial features of binary matroids and 4-regular graphs. The concept of isotropic system is a useful tool to study vertex-minors of graphs and yet it is not well known. I will give an introduction to isotropic systems.
Reinhard Diestel, Tangles of set separations: a novel clustering method and type recognition in machine learning
Zoom ID: 869 4632 6610 (ibsdimag)Traditional clustering identifies groups of objects that share certain qualities. Tangles do the converse: they identify groups of qualities that typically occur together. They can thereby discover, relate, and structure types: of behaviour, political views, texts, or proteins. Tangles offer a new, quantitative, paradigm for grouping phenomena rather than things. They can identify key phenomena …
Jungho Ahn (안정호), Well-partitioned chordal graphs with the obstruction set and applications
Room B232 IBS (기초과학연구원)We introduce a new subclass of chordal graphs that generalizes split graphs, which we call well-partitioned chordal graphs. Split graphs are graphs that admit a partition of the vertex set into cliques that can be arranged in a star structure, the leaves of which are of size one. Well-partitioned chordal graphs are a generalization of …
Extremal and Probabilistic Combinatorics (2021 KMS Spring Meeting)
A special session "Extremal and Probabilistic Combinatorics" at the 2021 KMS Spring Meeting is organized by Tuan Tran. URL: https://www.kms.or.kr/meetings/spring2021/ Speakers and Schedule All talks are on April 30. Joonkyung Lee (이준경), University College London Majority dynamics on sparse random graphs Dong Yeap Kang (강동엽), Unversity of Birmingham The Erdős-Faber-Lovász conjecture and related results Jinyoung …
Raul Lopes, Adapting the Directed Grid Theorem into an FPT Algorithm
Zoom ID: 869 4632 6610 (ibsdimag)The Grid Theorem of Robertson and Seymour is one of the most important tools in the field of structural graph theory, finding numerous applications in the design of algorithms for undirected graphs. An analogous version of the Grid Theorem in digraphs was conjectured by Johnson et al. , and proved by Kawarabayashi and Kreutzer . …
Hong Liu, Sublinear expander and embeddings sparse graphs
ZoomA notion of sublinear expander has played a central role in the resolutions of a couple of long-standing conjectures in embedding problems in graph theory, including e.g. the odd cycle problem of Erdős and Hajnal that the harmonic sum of odd cycle length in a graph diverges with its chromatic number. I will survey some …
Mark Siggers, The list switch homomorphism problem for signed graphs
Room B232 IBS (기초과학연구원)A signed graph is a graph in which each edge has a positive or negative sign. Calling two graphs switch equivalent if one can get from one to the other by the iteration of the local action of switching all signs on edges incident to a given vertex, we say that there is a switch …
Johannes Carmesin, A Whitney type theorem for surfaces: characterising graphs with locally planar embeddings
Zoom ID: 869 4632 6610 (ibsdimag)Given a graph, how do we construct a surface so that the graph embeds in that surface in an optimal way? Thomassen showed that for minimum genus as optimality criterion, this problem would be NP-hard. Instead of minimum genus, here we use local planarity -- and provide a polynomial algorithm. Our embedding method is based …
Pascal Gollin, Enlarging vertex-flames in countable digraphs
Room B232 IBS (기초과학연구원)A rooted digraph is a vertex-flame if for every vertex v there is a set of internally disjoint directed paths from the root to v whose set of terminal edges covers all ingoing edges of v. It was shown by Lovász that every finite rooted digraph admits a spanning subdigraph which is a vertex-flame and large, where the latter means …