,
Christian Komusiewicz
,
Frank Sommer
Creative Commons Attribution 3.0 Unported license
A graph G is weakly γ-closed if every induced subgraph of G contains one vertex v such that for each non-neighbor u of v it holds that |N(u)∩ N(v)| < γ. The weak closure γ(G) of a graph, recently introduced by Fox et al. [SIAM J. Comp. 2020], is the smallest number such that G is weakly γ-closed. This graph parameter is never larger than the degeneracy (plus one) and can be significantly smaller. Extending the work of Fox et al. [SIAM J. Comp. 2020] on clique enumeration, we show that several problems related to finding dense subgraphs, such as the enumeration of bicliques and s-plexes, are fixed-parameter tractable with respect to γ(G). Moreover, we show that the problem of determining whether a weakly γ-closed graph G has a subgraph on at least k vertices that belongs to a graph class 𝒢 which is closed under taking subgraphs admits a kernel with at most γ k² vertices. Finally, we provide fixed-parameter algorithms for Independent Dominating Set and Dominating Clique when parameterized by γ+k where k is the solution size.
@InProceedings{koana_et_al:LIPIcs.ISAAC.2020.20,
author = {Koana, Tomohiro and Komusiewicz, Christian and Sommer, Frank},
title = {{Computing Dense and Sparse Subgraphs of Weakly Closed Graphs}},
booktitle = {31st International Symposium on Algorithms and Computation (ISAAC 2020)},
pages = {20:1--20:17},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-173-3},
ISSN = {1868-8969},
year = {2020},
volume = {181},
editor = {Cao, Yixin and Cheng, Siu-Wing and Li, Minming},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ISAAC.2020.20},
URN = {urn:nbn:de:0030-drops-133646},
doi = {10.4230/LIPIcs.ISAAC.2020.20},
annote = {Keywords: Fixed-parameter tractability, c-closure, degeneracy, clique relaxations, bicliques, dominating set}
}