Limit Behavior of Locally Consistent Constraint Satisfaction Problems

نویسندگان

  • Manuel Bodirsky
  • Daniel Král
چکیده

An instance of a constraint satisfaction problem (CSP) is variable k-consistent if any subinstance with at most k variables has a solution. For a fixed constraint language L, ρk(L) is the largest ratio such that any variable k-consistent instance has a solution that satisfies at least a fraction of ρk(L) of the constraints. We provide an expression for the limit ρ(L) := limk→∞ ρk(L), and show that this limit coincides with the corresponding limit for constraint k-consistent instances, i.e., instances where all subinstances with at most k constraints have a solution. We also design an algorithm running in time polynomial in the size of input and 1/ε that for an input instance and a given ε either computes a solution that satisfies at least a fraction of ρ(L) − ε constraints or finds a set of inconsistent constraints whose size only depends on ǫ. Most of our results apply both to weighted and to unweighted instances of the constraint satisfaction problem.

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عنوان ژورنال:
  • SIAM J. Discrete Math.

دوره 25  شماره 

صفحات  -

تاریخ انتشار 2011