,
Ruben F. A. Verhaegh
Creative Commons Attribution 4.0 International license
For a fixed set ℱ of Boolean constraint types, a MinCSP(ℱ)-instance consists of a formula F that applies m constraints from ℱ to a set of n Boolean variables. The goal is to remove a minimum subset of constraint applications from F to make the remaining formula satisfiable. Previous work characterized how the choice of ℱ affects its polynomial-time solvability and approximability. We extend a recently introduced preprocessing framework for graph problems to the problem above. Rephrased in the context of CSPs, this framework defines a constraint application from a given formula F as c-essential if it is contained in all c-approximate solutions to F. Being able to efficiently detect these essential parts of a solution reduces the search space of any follow-up FPT algorithms parameterized by the solution size and yields an immediate asymptotic improvement to the runtime of such algorithms. In this work, we present a dichotomy theorem that distinguishes constraint sets ℱ for which c_ℱ-essential constraint applications can be detected efficiently for some c_{ℱ} ∈ 𝒪(1), from those for which this task is intractable under established complexity-theoretic conjectures. Our results show that for any set ℱ of bijunctive constraints, there is a polynomial-time algorithm that detects 𝒪(1)-essential constraint applications. This contrasts the fact that constant-factor approximating a bijunctive MinCSP(ℱ)-problem is intractable under the Unique Games Conjecture.
@InProceedings{jansen_et_al:LIPIcs.SWAT.2026.22,
author = {Jansen, Bart M. P. and Verhaegh, Ruben F. A.},
title = {{Search-Space Reduction for Boolean MinCSPs via Essential Constraints}},
booktitle = {20th Scandinavian Symposium on Algorithm Theory (SWAT 2026)},
pages = {22:1--22:17},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-421-5},
ISSN = {1868-8969},
year = {2026},
volume = {370},
editor = {Fraigniaud, Pierre},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SWAT.2026.22},
URN = {urn:nbn:de:0030-drops-260586},
doi = {10.4230/LIPIcs.SWAT.2026.22},
annote = {Keywords: fixed-parameter tractability, constraint satisfaction problems}
}