,
Moritz Jahn
,
Simon Knäuer
,
Matěj Konečný
,
Paul Winkler
Creative Commons Attribution 4.0 International license
Andréka and Maddux classified the relation algebras with at most 3 atoms, and in particular they showed that all of them are representable [Hajnal Andréka and Roger D. Maddux, 1994]. Hirsch and Cristiani showed that the network satisfaction problem (NSP) for each of these algebras is in P or NP-hard [Matteo Cristiani and Robin Hirsch, 2004]. The literature contains many results on representations of relation algebras; in particular, some relation algebras with four atoms are not representable. We extend the result of Cristiani and Hirsch to relation algebras with at most 4 atoms: the NSP is always either in P or NP-hard. To this end, we construct universal, fully universal, or even normal representations for these algebras, whenever possible.
@InProceedings{bodirsky_et_al:LIPIcs.ICALP.2026.168,
author = {Bodirsky, Manuel and Jahn, Moritz and Kn\"{a}uer, Simon and Kone\v{c}n\'{y}, Mat\v{e}j and Winkler, Paul},
title = {{The Network Satisfaction Problem for Relation Algebras with at Most 4 Atoms}},
booktitle = {53rd International Colloquium on Automata, Languages, and Programming (ICALP 2026)},
pages = {168:1--168:23},
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.2026.168},
URN = {urn:nbn:de:0030-drops-265564},
doi = {10.4230/LIPIcs.ICALP.2026.168},
annote = {Keywords: Constraint Satisfaction, Computational Complexity, Relation Algebras, Network Satisfaction, Normal Representations, Polynomial-Time Algorithms}
}
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