,
Yaowei Long
,
David Pidugu,
Thatchaphol Saranurak
,
Benyu Wang
Creative Commons Attribution 4.0 International license
We study connectivity oracle under vertex failures, one of the most fundamental graph data structures with many applications. We provide a new deterministic connectivity oracle that handles update in O(k⁶) time and answers query in O(k) time, while using 2^O(k²) n + O(k²n α_c(n)) space and k^O(k²) n + O(m + k³ n log² n + k⁶n log n) preprocessing time. Although some previous works achieve k² ⋅ n^o(1) update time and O(k) query time [Long and Saranurak, 2022; Yaowei Long and Yunfan Wang, 2024], the update time is still n-dependent, while oracles that have n-independent update and query times [Michal Pilipczuk et al., 2022; Jan van den Brand and Thatchaphol Saranurak, 2019] cannot achieve optimal O(k) query time [Monika Henzinger et al., 2015] and often have Ω(n²) space and processing time. Our solution would be the first vertex-failure connectivity oracle that achieves O(k) query time with update time completely independent of n, while improving space usage and having competitive preprocessing time.
@InProceedings{li_et_al:LIPIcs.ICALP.2026.139,
author = {Li, Xizhe and Long, Yaowei and Pidugu, David and Saranurak, Thatchaphol and Wang, Benyu},
title = {{Connectivity Oracle Under Vertex Failures by Shortcutting Unbreakable Decomposition}},
booktitle = {53rd International Colloquium on Automata, Languages, and Programming (ICALP 2026)},
pages = {139:1--139:20},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-428-4},
ISSN = {1868-8969},
year = {2026},
volume = {374},
editor = {Bhattacharya, Sayan and Nanongkai, Danupon and Benedikt, Michael and Puppis, Gabriele},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICALP.2026.139},
URN = {urn:nbn:de:0030-drops-265285},
doi = {10.4230/LIPIcs.ICALP.2026.139},
annote = {Keywords: Graphs, Fault tolerant, Oracles}
}