Elmar BĂ¶hler

A clone is a set of functions that is closed under generalized substitution.

The set FP of functions being computable deterministically in polynomial

time is such a clone. It is well-known that the set of subclones of every

clone forms a lattice. We study the lattice below FP, which ...
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Hubie Chen

The constraint satisfaction problem (CSP) is a convenient framework for modelling search problems; the CSP involves deciding, given a set of constraints on variables, whether or not there is an assignment to the variables satisfying all of the constraints. This paper is concerned with the quantified constraint satisfaction problem (QCSP), ... more >>>

Benoit Larose, Pascal Tesson, Pascal Tesson

We present algebraic conditions on constraint languages \Gamma

that ensure the hardness of the constraint satisfaction problem

CSP(\Gamma) for complexity classes L, NL, P, NP and Mod_pL.

These criteria also give non-expressibility results for various

restrictions of Datalog. Furthermore, we show that if

CSP(\Gamma) is not first-order definable then it ...
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Andrei A. Bulatov

The Counting Constraint Satisfaction Problem (#CSP(H)) over a finite

relational structure H can be expressed as follows: given a

relational structure G over the same vocabulary,

determine the number of homomorphisms from G to H.

In this paper we characterize relational structures H for which

#CSP(H) can be solved in ...
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Suguru Tamaki, Yuichi Yoshida

A temporal constraint language $\Gamma$ is a set of relations with first-order definitions in $({\mathbb{Q}}; <)$. Let CSP($\Gamma$) denote the set of constraint satisfaction problem instances with relations from $\Gamma$. CSP($\Gamma$) admits robust approximation if, for any $\varepsilon \geq 0$, given a $(1-\varepsilon)$-satisfiable instance of CSP($\Gamma$), we can compute an ... more >>>