On the Parameterized Complexity of the Connected Flow and Many Visits TSP Problem

Isja Mannens, Jesper Nederlof, Céline Swennenhuis, Krisztina Szilágyi

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

Abstract

We study a variant of Min Cost Flow in which the flow needs to be connected. Specifically, in the Connected Flow problem one is given a directed graph G, along with a set of demand vertices D⊆ V(G) with demands dem: D→ N, and costs and capacities for each edge. The goal is to find a minimum cost flow that satisfies the demands, respects the capacities and induces a (strongly) connected subgraph. This generalizes previously studied problems like the (Many Visits) TSP. We study the parameterized complexity of Connected Flow parameterized by |D|, the treewidth tw and by vertex cover size k of G and provide: 1.NP-completeness already for the case | D| = 2 with only unit demands and capacities and no edge costs, and fixed-parameter tractability if there are no capacities,2.a fixed-parameter tractable O(kO ( k )) time algorithm for the general case, and a kernel of size polynomial in k for the special case of Many Visits TSP,3.a | V(G) |O ( t w ) time algorithm and a matching | V(G) |o ( t w ) time conditional lower bound conditioned on the Exponential Time Hypothesis. To achieve some of our results, we significantly extend an approach by Kowalik et al. [ESA’20].

Original languageEnglish
Title of host publicationGraph-Theoretic Concepts in Computer Science
Subtitle of host publication47th International Workshop, WG 2021 Warsaw, Poland, June 23–25, 2021 Revised Selected Papers
EditorsLukasz Kowalik, Michal Pilipczuk, Pawel Rzazewski
PublisherSpringer
Pages52-79
Number of pages28
ISBN (Electronic)978-3-030-86838-3
ISBN (Print)978-3-030-86837-6
DOIs
Publication statusPublished - 23 Jun 2021

Publication series

NameLecture Notes in Computer Science
PublisherSpringer, Cham
Volume12911
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349

Bibliographical note

Funding Information:
Supported by the project CRACKNP that has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 853234) and by the Netherlands Organization for Scientific Research under project no. 613.009.031b.

Publisher Copyright:
© 2021, Springer Nature Switzerland AG.

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