Xizhi Liu, Hypergraph Turán problem: from 1 to ∞

Zoom ID: 870 0312 9412 (ibsecopro)

One interesting difference between (nondegenerate) Graph Turán problem and Hypergraph Turán problem is that the hypergraph families can have at least two very different extremal constructions. In this talk, we will look at some recent progress and approaches to constructing hypergraph families with at least two different extremal constructions. Based on some joint work with

Eric Vigoda, Computational phase transition and MCMC algorithms

Room B332 IBS (기초과학연구원)

This talk will highlight recent results establishing a beautiful computational phase transition for approximate counting/sampling in (binary) undirected graphical models (such as the Ising model or on weighted independent sets). The computational problem is to sample from the equilibrium distribution of the model or equivalently approximate the corresponding normalizing factor known as the partition function. We show that when correlations die

Jinyoung Park (박진영), Thresholds 1/2

Room B332 IBS (기초과학연구원)

Thresholds for increasing properties of random structures are a central concern in probabilistic combinatorics and related areas. In 2006, Kahn and Kalai conjectured that for any nontrivial increasing property on a finite set, its threshold is never far from its "expectation-threshold," which is a natural (and often easy to calculate) lower bound on the threshold.

Jinyoung Park (박진영), Thresholds 2/2

Room B332 IBS (기초과학연구원)

Thresholds for increasing properties of random structures are a central concern in probabilistic combinatorics and related areas. In 2006, Kahn and Kalai conjectured that for any nontrivial increasing property on a finite set, its threshold is never far from its "expectation-threshold," which is a natural (and often easy to calculate) lower bound on the threshold.

Seunghun Lee (이승훈), Inscribable order types

Room B332 IBS (기초과학연구원)

We call an order type inscribable if it is realized by a point configuration where all extreme points are all on a circle. In this talk, we investigate inscribability of order types. We first show that every simple order type with at most 2 interior points is inscribable, and that the number of such order

Lars Jaffke, Taming graphs with no large creatures and skinny ladders

Zoom ID: 869 4632 6610 (ibsdimag)

We confirm a conjecture of Gartland and Lokshtanov : if for a hereditary graph class $\mathcal{G}$ there exists a constant $k$ such that no member of $\mathcal{G}$ contains a $k$-creature as an induced subgraph or a $k$-skinny-ladder as an induced minor, then there exists a polynomial $p$ such that every $G \in \mathcal{G}$ contains at

Eun Jung Kim (김은정), Directed flow-augmentation

Room B332 IBS (기초과학연구원)

We show a flow-augmentation algorithm in directed graphs: There exists a polynomial-time algorithm that, given a directed graph G, two integers $s,t\in V(G)$, and an integer $k$, adds (randomly) to $G$ a number of arcs such that for every minimal st-cut $Z$ in $G$ of size at most $k$, with probability $2^{−\operatorname{poly}(k)}$ the set $Z$

Akash Kumar, Random walks and Forbidden Minors

Zoom ID: 870 0312 9412 (ibsecopro)

Random walks and spectral methods have had a strong influence on modern graph algorithms as evidenced by the extensive literature on the subject. In this talk, I will present how random walks helped make progress on algorithmic problems on planar graphs. In particular, I show how random walk based (i.e., spectral) approaches led to progress

IBS 이산수학그룹 Discrete Mathematics Group
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