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The Network Satisfaction Problem for Relation Algebras with at most 4 Atoms

Published: July 12, 2025 | arXiv ID: 2507.09324v1

By: Manuel Bodirsky , Moritz Jahn , Matěj Konečný and more

Potential Business Impact:

Solves hard math problems about relationships.

Andr\'eka and Maddux classified the relation algebras with at most 3 atoms, and in particular they showed that all of them are representable. Hirsch and Cristiani showed that the network satisfaction problem (NSP) for each of these algebras is in P or NP-hard. There are relation algebras with 4 atoms that are not representable, and there are many results in the literature about representations and non-representability of relation algebras with at most 4 atoms. We extend the result of Hirsch and Cristiani 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.

Page Count
68 pages

Category
Mathematics:
Rings and Algebras