English

Disjoint paths in unions of tournaments

Combinatorics 2018-12-27 v2

Abstract

Given kk pairs of vertices (si,ti)  (1ik)(s_i,t_i)\;(1\le i\le k) of a digraph GG, how can we test whether there exist vertex-disjoint directed paths from sis_i to tit_i for 1ik1\le i\le k? This is NP-complete in general digraphs, even for k=2k = 2, but in an earlier paper we proved that for all fixed kk, there is a polynomial-time algorithm to solve the problem if GG is a tournament (or more generally, a semicomplete digraph). Here we prove that for all fixed kk there is a polynomial-time algorithm to solve the problem when V(G)V(G) is partitioned into a bounded number of sets each inducing a semicomplete digraph (and we are given the partition).

Keywords

Cite

@article{arxiv.1604.02317,
  title  = {Disjoint paths in unions of tournaments},
  author = {Maria Chudnovsky and Alex Scott and Paul Seymour},
  journal= {arXiv preprint arXiv:1604.02317},
  year   = {2018}
}