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 language | English |
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Title of host publication | Graph-Theoretic Concepts in Computer Science |
Subtitle of host publication | 47th International Workshop, WG 2021 Warsaw, Poland, June 23–25, 2021 Revised Selected Papers |
Editors | Lukasz Kowalik, Michal Pilipczuk, Pawel Rzazewski |
Publisher | Springer |
Pages | 52-79 |
Number of pages | 28 |
ISBN (Electronic) | 978-3-030-86838-3 |
ISBN (Print) | 978-3-030-86837-6 |
DOIs | |
Publication status | Published - 23 Jun 2021 |
Publication series
Name | Lecture Notes in Computer Science |
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Publisher | Springer, Cham |
Volume | 12911 |
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.