We present a dual fault-tolerant distance oracle for undirected and unweighted graphs. Given a set F of two edges, as well as a source node s and a destination node t, our oracle returns the length of the shortest path from s to t that avoids F in O(1) time with a high probability. The space complexity of our oracle is Õ(n²) , making it nearly optimal in terms of both space and query time. Prior to our work, Pettie and Duan [SODA 2009] designed a dual fault-tolerant distance oracle that required Õ(n²) space and O(log n) query time. In addition to improving the query time, our oracle is much simpler than the previous approach.
@InProceedings{dey_et_al:LIPIcs.ESA.2024.45, author = {Dey, Dipan and Gupta, Manoj}, title = {{Near Optimal Dual Fault Tolerant Distance Oracle}}, booktitle = {32nd Annual European Symposium on Algorithms (ESA 2024)}, pages = {45:1--45:23}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-338-6}, ISSN = {1868-8969}, year = {2024}, volume = {308}, editor = {Chan, Timothy and Fischer, Johannes and Iacono, John 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.2024.45}, URN = {urn:nbn:de:0030-drops-211164}, doi = {10.4230/LIPIcs.ESA.2024.45}, annote = {Keywords: Distance Sensitive Oracle, Dual Fault Distance Oracle} }
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