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res:
bibo_abstract:
- A class of valued constraint satisfaction problems (VCSPs) is characterised by
a valued constraint language, a fixed set of cost functions on a finite domain.
An instance of the problem is specified by a sum of cost functions from the language
with the goal to minimise the sum. We study which classes of finite-valued languages
can be solved exactly by the basic linear programming relaxation (BLP). Thapper
and Živný showed [20] that if BLP solves the language then the language admits
a binary commutative fractional polymorphism. We prove that the converse is also
true. This leads to a necessary and a sufficient condition which can be checked
in polynomial time for a given language. In contrast, the previous necessary and
sufficient condition due to [20] involved infinitely many inequalities. More recently,
Thapper and Živný [21] showed (using, in particular, a technique introduced in
this paper) that core languages that do not satisfy our condition are NP-hard.
Taken together, these results imply that a finite-valued language can either be
solved using Linear Programming or is NP-hard.@eng
bibo_authorlist:
- foaf_Person:
foaf_givenName: Vladimir
foaf_name: Kolmogorov, Vladimir
foaf_surname: Kolmogorov
foaf_workInfoHomepage: http://www.librecat.org/personId=3D50B0BA-F248-11E8-B48F-1D18A9856A87
bibo_doi: 10.1007/978-3-642-39206-1_53
bibo_issue: '1'
bibo_volume: 7965
dct_date: 2013^xs_gYear
dct_language: eng
dct_publisher: Springer@
dct_title: 'The power of linear programming for finite-valued CSPs: A constructive
characterization@'
...