,
Zhenwei Liu
,
Nicole Megow
,
Guochuan Zhang
Creative Commons Attribution 4.0 International license
We study the problem of guaranteeing the connectivity of a given graph by protecting or strengthening edges. Herein, a protected edge is assumed to be robust and will not fail, which features a non-uniform failure model. We introduce the (p,q)-Steiner-Connectivity Preservation problem where we protect a minimum-cost set of edges such that the underlying graph maintains p-edge-connectivity between given terminal pairs against edge failures, assuming at most q unprotected edges can fail. We design polynomial-time exact algorithms for the cases where p and q are small and approximation algorithms for general values of p and q. Additionally, we show that when both p and q are part of the input, even deciding whether a given solution is feasible is NP-complete. This hardness also carries over to Flexible Network Design, a research direction that has gained significant attention. In particular, previous work focuses on problem settings where either p or q is constant, for which our new hardness result now provides justification.
@InProceedings{hommelsheim_et_al:LIPIcs.STACS.2025.51,
author = {Hommelsheim, Felix and Liu, Zhenwei and Megow, Nicole and Zhang, Guochuan},
title = {{Protecting the Connectivity of a Graph Under Non-Uniform Edge Failures}},
booktitle = {42nd International Symposium on Theoretical Aspects of Computer Science (STACS 2025)},
pages = {51:1--51:21},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-365-2},
ISSN = {1868-8969},
year = {2025},
volume = {327},
editor = {Beyersdorff, Olaf and Pilipczuk, Micha{\l} and Pimentel, Elaine and Thắng, Nguy\~{ê}n Kim},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.STACS.2025.51},
URN = {urn:nbn:de:0030-drops-228761},
doi = {10.4230/LIPIcs.STACS.2025.51},
annote = {Keywords: Network Design, Edge Failures, Graph Connectivity, Approximation Algorithms}
}