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 …
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Seminars and Colloquiums
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, …
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 …
Benjamin Bumpus, Directed branch-width: A directed analogue of tree-width
Zoom ID: 869 4632 6610 (ibsdimag)Many problems that are NP-hard in general become tractable on `structurally recursive’ graph classes. For example, consider classes of bounded tree- or clique-width. Since the 1990s, many directed analogues of …
Ben Lund, Limit shape of lattice Zonotopes
Room B232 IBS (기초과학연구원)A convex lattice polytope is the convex hull of a set of integral points. Vershik conjectured the existence of a limit shape for random convex lattice polygons, and three proofs …
Dimitrios M. Thilikos, Bounding Obstructions sets: the cases of apices of minor closed classes
Zoom ID: 869 4632 6610 (ibsdimag)Given a minor-closed graph class ${\cal G}$, the (minor) obstruction of ${\cal G}$ is the set of all minor-minimal graphs not in ${\cal G}$. Given a non-negative integer $k$, we define …
Doowon Koh (고두원), Mattila-Sjölin type functions: A finite field model
Room B232 IBS (기초과학연구원)Let $\mathbb{F}_q$ be a finite field of order $q$ which is a prime power. In the finite field setting, we say that a function $\phi\colon \mathbb{F}_q^d\times \mathbb{F}_q^d\to \mathbb{F}_q$ is a Mattila-Sjölin …
Adam Zsolt Wagner, Constructions in combinatorics via neural networks
Zoom ID: 869 4632 6610 (ibsdimag)Recently, significant progress has been made in the area of machine learning algorithms, and they have quickly become some of the most exciting tools in a scientist’s toolbox. In particular, …
O-joung Kwon (권오정), Classes of intersection digraphs with good algorithmic properties
Zoom ID: 875 9395 3555 (relay) [CLOSED]An intersection digraph is a digraph where every vertex $v$ is represented by an ordered pair $(S_v, T_v)$ of sets such that there is an edge from $v$ to $w$ …
Alan Lew, Representability and boxicity of simplicial complexes
Zoom ID: 869 4632 6610 (ibsdimag)An interval graph is the intersection graph of a family of intervals in the real line. Motivated by problems in ecology, Roberts defined the boxicity of a graph G to …