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Smooth approximations and relational width collapses
Publikationstyp
Conference Paper
Date Issued
2021-07
Sprache
English
First published in
Number in series
198
Article Number
138
Citation
48th International Colloquium on Automata, Languages, and Programming (ICALP 2021) 198: 138 (2021)
Contribution to Conference
Publisher DOI
Scopus ID
Publisher
Schloss Dagstuhl - Leibniz-Zentrum für Informatik GmbH, Dagstuhl Publishing
We prove that relational structures admitting specific polymorphisms (namely, canonical pseudo- WNU operations of all arities n ≥ 3) have low relational width. This implies a collapse of the bounded width hierarchy for numerous classes of infinite-domain CSPs studied in the literature. Moreover, we obtain a characterization of bounded width for first-order reducts of unary structures and a characterization of MMSNP sentences that are equivalent to a Datalog program, answering a question posed by Bienvenu et al.. In particular, the bounded width hierarchy collapses in those cases as well.
Subjects
Bounded width
Constraint satisfaction problems
Local consistency
Polymorphisms
Smooth approximations