,
Clément Legrand-Duchesne
,
Reem Mahmoud,
Amer E. Mouawad
,
Yoshio Okamoto
,
Vinicius F. dos Santos
,
Tom C. van der Zanden
Creative Commons Attribution 4.0 International license
We study the problem of reconfiguring one minimum s-t-separator A into another minimum s-t-separator B in some n-vertex graph G containing two non-adjacent vertices s and t. We consider several variants of the problem as we focus on both the token sliding and token jumping models. Our first contribution is a polynomial-time algorithm that computes (if one exists) a minimum-length sequence of slides transforming A into B. We additionally establish that the existence of a sequence of jumps (which need not be of minimum length) can be decided in polynomial time (by an algorithm that also outputs a witnessing sequence when one exists). In contrast, and somewhat surprisingly, we show that deciding if a sequence of at most 𝓁 jumps can transform A into B is an NP-complete problem. To complement this negative result, we investigate the parameterized complexity of what we believe to be the two most natural parameterized counterparts of the latter problem; in particular, we study the problem of computing a minimum-length sequence of jumps when parameterized by the size k of the minimum s-t-separators and when parameterized by the number 𝓁 of jumps. For the first parameterization, we show that the problem is fixed-parameter tractable, but does not admit a polynomial kernel unless NP ⊆ coNP/poly. We complete the picture by designing a kernel with 𝒪(𝓁²) vertices and edges for the length 𝓁 of the sequence as a parameter.
@InProceedings{c.m.gomes_et_al:LIPIcs.IPEC.2023.9,
author = {C. M. Gomes, Guilherme and Legrand-Duchesne, Cl\'{e}ment and Mahmoud, Reem and Mouawad, Amer E. and Okamoto, Yoshio and F. dos Santos, Vinicius and C. van der Zanden, Tom},
title = {{Minimum Separator Reconfiguration}},
booktitle = {18th International Symposium on Parameterized and Exact Computation (IPEC 2023)},
pages = {9:1--9:12},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-305-8},
ISSN = {1868-8969},
year = {2023},
volume = {285},
editor = {Misra, Neeldhara and Wahlstr\"{o}m, Magnus},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.IPEC.2023.9},
URN = {urn:nbn:de:0030-drops-194288},
doi = {10.4230/LIPIcs.IPEC.2023.9},
annote = {Keywords: minimum separators, combinatorial reconfiguration, parameterized complexity, kernelization}
}