Organizatorzy

dr hab. Michał Pilipczuk, prof. ucz.

Informacje

piątki, 14:15 , sala: 5060

Strona domowa

https://semalgo.wordpress.com/

Lista referatów

12 grudnia 2019 12:15
Erik Jan van Leeuwen (Utrecht University)
On Geometric Set Cover for Orthants
We study Set Cover for orthants: Given a set of points in a d-dimensional Euclidean space and a set of orthants of the form (-infty,p_1] x ... x (-infty,p_d], select a minimum number of orthants …
28 listopada 2019 12:15
Petteri Kaski (Department of Computer Science, Aalto University)
Probabilistic tensors and opportunistic Boolean matrix multiplication
We introduce probabilistic extensions of classical deterministic measures of algebraic complexity of a tensor, such as the rank and the border rank. We show that these probabilistic extensions satisfy various natural and algorithmically serendipitous properties, …
14 listopada 2019 12:15
Piotr Sankowski (University of Warsaw)
Walking Randomly, Massively, and Efficiently
We introduce an approach that allows for efficiently generating many independent random walks in big graph models, such as the Massive Parallel Computation (MPC) model. We consider the case where the space per machine is …
7 listopada 2019 12:15
Marcin Pilipczuk (University of Warsaw)
A Polynomial-Time Approximation Scheme for Facility Location on Planar Graphs
We consider the classic Facility Location problem on planar graphs (non-uniform, uncapacitated). Given an edge-weighted planar graph $G$, a set of clients $C\subseteq V(G)$, a set of facilities $F \subseteq V(G)$, and opening costs $w …
31 października 2019 12:15
François Dross (University of Warsaw)
Trees in tournaments
A tournament is an orientation of a complete graph. A digraph is n-unavoidable if it is contained (as a subdigraph) in every tournament of order n. The unavoidability of a digraph D is the minimum …
24 października 2019 13:00
Solon Pissis (CWI)
Even Faster Elastic-Degenerate String Matching via Fast Matrix Multiplication
An elastic-degenerate (ED) string is a sequence of n sets of strings of total length N, which was recently proposed to model a set of similar sequences. The ED string matching (EDSM) problem is to …
24 października 2019 12:15
Krzysztof Nowicki (UWr)
Faster Algorithms for Edge Connectivity via Random 2-Out Contractions
We provide a simple new randomized contraction approach to the global minimum cut problem for simple undirected graphs. The contractions exploit 2-out edge sampling from each vertex rather than the standard uniform edge sampling. We …
17 października 2019 12:15
Stéphane Bessy (LIRMM Montpellier)
Triangle and cycle packing in tournaments: complexity and algorithms
Given a tournament T and a positive integer k, we study different question dealing with packing (oriented) cycles in tournament: does T contain k vertex-disjoint cycles (k-VCT)? k arc-disjoint cycles (k-ACT)? k-arc-disjoint triangles (k-ATT)?, where …
10 października 2019 12:15
Edouard Bonnet (ENS Lyon)
Parameterized Complexity of Grundy Coloring and its variants
(Connected/Partial/Weak) Grundy Coloring, b-Coloring, b-Chromatic Core, etc. are maximization coloring problems, where one asks for the worst case of a first-fit coloring strategy. They were introduced to analyze if some coloring heuristics have performance guarantee. …
19 czerwca 2019 12:15
Karol Węgrzycki (MIMUW)
Recent Progress on Approximate APSP
In this talk we prove the equivalence of computing the approximate (min,+)-product of two $n \times n$ matrices with arbitrary values and (min,max)-product. This yields a first subcubic strongly polynomial approximation for the all-pairs shortest …
13 czerwca 2019 12:15
Anita Liebenau (University of New South Wales)
Enumerating graphs and other discrete structures by degree sequence
How many d-regular graphs are there on n vertices? What is the probability that G(n,p) has a specific given degree sequence, where G(n,p) is the homogeneous random graph in which every edge is inserted with …
30 maja 2019 12:15
Anish Mukherjee (Chennai Mathematical Institute, India)
Solving connectivity problems via basic Linear Algebra
We consider some classical graph connectivity problems like reachability, shortest path and disjoint paths in different settings. For the first two problems, we show efficient parallel algorithms in the dynamic framework, confirming a conjecture of …
23 maja 2019 12:15
Piotr Skowron (University of Warsaw)
Fairness and Public Goods: the Case of Multiwinner Rules
An instance of a multiwinner election consists of a set of alternatives, a population of voters---each voter approves a subset of alternatives, and the desired committee size k; the goal is to select a committee …
21 lutego 2019 12:15
Laszlo Kozma (Freie Universität Berlin)
Selection from heaps, row-sorted matrices, and X+Y, using soft heaps
We use soft heaps to obtain simpler optimal algorithms for selecting the k-th smallest item from a heap-ordered tree, from a collection of sorted lists, and from X+Y. Our results match, and in some ways extend classical results …
24 stycznia 2019 12:15
Karolina Okrasa (Politechnika Warszawska)
Subexponential algorithms for locally constrained homomorphism problems in string graphs
We consider the complexity of finding weighted homomorphisms from string graphs with n vertices to a fixed graph H. We show that there exists an algorithm solving this problem in subexponential time, if H has no two vertices …