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Valued constraint satisfaction problems (VCSPs) are discrete optimisation problems with the objective function given as a sum of fixed-arity functions; the values are rational numbers or infinity.
In Boolean surjective VCSPs variables take on labels from D={0,1} and an optimal assignment is required to use both labels from D. A classic example is the global min-cut problem in graphs. Building on the work of Uppman, we establish a dichotomy theorem and thus give a complete complexity classification of Boolean surjective VCSPs. The newly discovered tractable case has an interesting structure related to projections of downsets and upsets. Our work generalises the dichotomy for {0,infinity}-valued constraint languages corresponding to CSPs) obtained by Creignou and Hebrard, and the dichotomy for {0,1}-valued constraint languages (corresponding to Min-CSPs) obtained by Uppman.
@InProceedings{fulla_et_al:LIPIcs.MFCS.2017.4,
author = {Fulla, Peter and Zivny, Stanislav},
title = {{The Complexity of Boolean Surjective General-Valued CSPs}},
booktitle = {42nd International Symposium on Mathematical Foundations of Computer Science (MFCS 2017)},
pages = {4:1--4:14},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-046-0},
ISSN = {1868-8969},
year = {2017},
volume = {83},
editor = {Larsen, Kim G. and Bodlaender, Hans L. and Raskin, Jean-Francois},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.MFCS.2017.4},
URN = {urn:nbn:de:0030-drops-80623},
doi = {10.4230/LIPIcs.MFCS.2017.4},
annote = {Keywords: constraint satisfaction problems, surjective CSP, valued CSP, min-cut, polymorphisms, multimorphisms}
}