Organizatorzy

dr hab. Michał Pilipczuk, prof. ucz.

Informacje

piątki, 14:15 , sala: 5060

Strona domowa

https://students.mimuw.edu.pl/~kd417818/algorithms-seminar/

Dziedziny badań

Algorytmika

Lista referatów

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 …
17 stycznia 2019 12:15
Adrian Vladu (Boston University)
Discrepancy and Optimization
We consider the problem of minimizing the discrepancy of a set system. In 1985, Spencer proved that for m sets over a universe of n elements, one can always achieve a coloring with discrepancy O(sqrt(n …
29 listopada 2018 12:15
Krszysztof Fleszar (Univerisity of Warsaw)
A PTAS for TSP with hyperplane neighborhoods
A PTAS for TSP with hyperplane neighborhoods In TSP with neighborhoods, we are asked for a shortest tour visiting a given set of regions (i.e., neighborhoods). When the neighborhoods are lines in 2D, the problem …
25 października 2018 12:15
Stéphan Thomassé (ENS Lyon)
EPTAS for Max Clique on Disks and Unit Balls
We propose a polynomial-time algorithm which takes as input a finite set of points of R3 and computes, up to arbitrary precision, a maximum subset with diameter at most 1. More precisely, we give the …
11 października 2018 12:15
Paweł Rzążewski (MIMI PW)
Finding list homomorphisms from bounded-treewidth graphs to reflexive graphs: a complete complexity characterization
In the list homomorphism problem, the input consists of two graphs G and H, together with a list L(v) \subseteq V(H) for every vertex v\in V(G). The task is to find a homomorphism \phi:V(G)\to V(H) …