,
Asaf Petruschka
Creative Commons Attribution 4.0 International license
We present a compact labeling scheme for determining whether a designated set of terminals in a graph remains connected after any f (or less) vertex failures occur. An f-FT Steiner connectivity labeling scheme for an n-vertex graph G = (V,E) with terminal set U ⊆ V provides labels to the vertices of G, such that given only the labels of any subset F ⊆ V with |F| ≤ f, one can determine if U remains connected in G-F. The main complexity measure is the maximum label length.
The special case U = V of global connectivity has been recently studied by Jiang, Parter, and Petruschka [Yonggang Jiang et al., 2025], who provided labels of n^{1-1/f} ⋅ poly(f,log n) bits. This is near-optimal (up to poly(f,log n) factors) by a lower bound of Long, Pettie and Saranurak [Yaowei Long et al., 2025]. Our scheme achieves labels of |U|^{1-1/f} ⋅ poly(f, log n) for general U ⊆ V, which is near-optimal for any given size |U| of the terminal set. To handle terminal sets, our approach differs from [Yonggang Jiang et al., 2025]. We use a well-structured Steiner tree for U produced by a decomposition theorem of Duan and Pettie [Ran Duan and Seth Pettie, 2020], and bypass the need for Nagamochi-Ibaraki sparsification [Hiroshi Nagamochi and Toshihide Ibaraki, 1992].
@InProceedings{bhanja_et_al:LIPIcs.ESA.2025.44,
author = {Bhanja, Koustav and Petruschka, Asaf},
title = {{Near-Optimal Vertex Fault-Tolerant Labels for Steiner Connectivity}},
booktitle = {33rd Annual European Symposium on Algorithms (ESA 2025)},
pages = {44:1--44:13},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-395-9},
ISSN = {1868-8969},
year = {2025},
volume = {351},
editor = {Benoit, Anne and Kaplan, Haim and Wild, Sebastian and Herman, Grzegorz},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ESA.2025.44},
URN = {urn:nbn:de:0030-drops-245123},
doi = {10.4230/LIPIcs.ESA.2025.44},
annote = {Keywords: Fault Tolerance, Labeling Schemes, Steiner Connectivity}
}