O'Reach: Even Faster Reachability in Large Graphs

Kathrin Hanauer, Christian Schulz, Jonathan Trummer

Veröffentlichungen: Beitrag in FachzeitschriftArtikelPeer Reviewed

Abstract

One of the most fundamental problems in computer science is the reachability problem: Given a directed graph and two vertices s and t, can sreach t via a path? We revisit existing techniques and combine them with new approaches to support a large portion of reachability queries in constant time using a linear-sized reachability index. Our new algorithm O’Reach can be easily combined with previously developed solutions for the problem or run standalone.

In a detailed experimental study, we compare a variety of algorithms with respect to their index-building and query times as well as their memory footprint on a diverse set of instances. Our experiments indicate that the query performance often depends strongly not only on the type of graph but also on the result, i.e., reachable or unreachable. Furthermore, we show that previous algorithms are significantly sped up when combined with our new approach in almost all scenarios. Surprisingly, due to cache effects, a higher investment in space doesn’t necessarily pay off: Reachability queries can often be answered even faster than single memory accesses in a precomputed full reachability matrix.
OriginalspracheEnglisch
Aufsatznummer4.2
Seiten (von - bis)1-27
Seitenumfang28
FachzeitschriftJournal of Experimental Algorithmics
Jahrgang27
Ausgabenummer5
DOIs
PublikationsstatusVeröffentlicht - 21 Okt. 2022

ÖFOS 2012

  • 102031 Theoretische Informatik

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