The c-packedness property, proposed in 2010, is a geometric property that captures the spatial distribution of a set of edges. Despite the recent interest in c-packedness, its utility has so far been limited to Fréchet distance problems. An open problem is whether a wider variety of algorithmic and data structure problems can be solved efficiently under the c-packedness assumption, and more specifically, on c-packed graphs. In this paper, we prove two fundamental properties of c-packed graphs: that there exists a linear-size well-separated pair decomposition under the graph metric, and there exists a constant size balanced separator. We then apply these fundamental properties to obtain a small tree cover for the metric space and distance oracles under the shortest path metric. In particular, we obtain a tree cover of constant size, an exact distance oracle of near-linear size and an approximate distance oracle of linear size.
@InProceedings{deryckere_et_al:LIPIcs.WADS.2025.21, author = {Deryckere, Lindsey and Gudmundsson, Joachim and van Renssen, Andr\'{e} and Sha, Yuan and Wong, Sampson}, title = {{A WSPD, Separator and Small Tree Cover for c-Packed Graphs}}, booktitle = {19th International Symposium on Algorithms and Data Structures (WADS 2025)}, pages = {21:1--21:15}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-398-0}, ISSN = {1868-8969}, year = {2025}, volume = {349}, editor = {Morin, Pat and Oh, Eunjin}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.WADS.2025.21}, URN = {urn:nbn:de:0030-drops-242529}, doi = {10.4230/LIPIcs.WADS.2025.21}, annote = {Keywords: Well-separated pair decomposition, separator, tree cover, distance oracles, realistic graphs} }
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