License: Creative Commons Attribution 3.0 Unported license (CC BY 3.0)
When quoting this document, please refer to the following
DOI: 10.4230/LIPIcs.IPEC.2020.12
URN: urn:nbn:de:0030-drops-133156
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Fomin, Fedor V. ; Golovach, Petr A. ; Lochet, William ; Misra, Pranabendu ; Saurabh, Saket ; Sharma, Roohani

Parameterized Complexity of Directed Spanner Problems

LIPIcs-IPEC-2020-12.pdf (0.6 MB)


We initiate the parameterized complexity study of minimum t-spanner problems on directed graphs. For a positive integer t, a multiplicative t-spanner of a (directed) graph G is a spanning subgraph H such that the distance between any two vertices in H is at most t times the distance between these vertices in G, that is, H keeps the distances in G up to the distortion (or stretch) factor t. An additive t-spanner is defined as a spanning subgraph that keeps the distances up to the additive distortion parameter t, that is, the distances in H and G differ by at most t. The task of Directed Multiplicative Spanner is, given a directed graph G with m arcs and positive integers t and k, decide whether G has a multiplicative t-spanner with at most m-k arcs. Similarly, Directed Additive Spanner asks whether G has an additive t-spanner with at most m-k arcs. We show that
- Directed Multiplicative Spanner admits a polynomial kernel of size ?(k⁴t⁵) and can be solved in randomized (4t)^k⋅ n^?(1) time,
- Directed Additive Spanner is W[1]-hard when parameterized by k even if t = 1 and the input graphs are restricted to be directed acyclic graphs. The latter claim contrasts with the recent result of Kobayashi from STACS 2020 that the problem for undirected graphs is FPT when parameterized by t and k.

BibTeX - Entry

  author =	{Fedor V. Fomin and Petr A. Golovach and William Lochet and Pranabendu Misra and Saket Saurabh and Roohani Sharma},
  title =	{{Parameterized Complexity of Directed Spanner Problems}},
  booktitle =	{15th International Symposium on Parameterized and Exact Computation (IPEC 2020)},
  pages =	{12:1--12:11},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-172-6},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{180},
  editor =	{Yixin Cao and Marcin Pilipczuk},
  publisher =	{Schloss Dagstuhl--Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{},
  URN =		{urn:nbn:de:0030-drops-133156},
  doi =		{10.4230/LIPIcs.IPEC.2020.12},
  annote =	{Keywords: Graph spanners, directed graphs, parameterized complexity, kernelization}

Keywords: Graph spanners, directed graphs, parameterized complexity, kernelization
Collection: 15th International Symposium on Parameterized and Exact Computation (IPEC 2020)
Issue Date: 2020
Date of publication: 04.12.2020

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