2026-09-21T06:04:44Z https://drops.dagstuhl.de/oai

oai:drops-oai.dagstuhl.de:19803 2026-09-05T16:17:11Z ddc:004 open_access

Subgraph Enumeration in Optimal I/O Complexity Deng, Shiyuan Tao, Yufei Subgraph Enumeration Conjunctive Queries External Memory Algorithms Given a massive data graph G = (V, E) and a small pattern graph Q, the goal of subgraph enumeration is to list all the subgraphs of G isomorphic to Q. In the external memory (EM) model, it is well-known that every indivisible algorithm must perform Ω({|E|^ρ}/{M^{ρ-1} B}) I/Os in the worst case, where M represents the number of words in (internal) memory, B denotes the number of words in a disk block, and ρ is the fractional edge covering number of Q. It has been a longstanding open problem to design an algorithm to match this lower bound. The state of the art is an algorithm in ICDT'23 that achieves an I/O complexity of O({|E|^ρ}/{M^{ρ-1} B} log_{M/B} |E|/B) with high probability. In this paper, we remove the log_{M/B} |E|/B factor, thereby settling the open problem when randomization is permitted. Schloss Dagstuhl – Leibniz-Zentrum für Informatik Shiyuan Deng and Yufei Tao 2024 Is Part Of LIPIcs, Volume 290, 27th International Conference on Database Theory (ICDT 2024) InProceedings Text doc-type:ResearchArticle publishedVersion application/pdf doi:10.4230/LIPIcs.ICDT.2024.21 urn:nbn:de:0030-drops-198033 https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2024.21 eng https://creativecommons.org/licenses/by/4.0/legalcode