The deductive method reduces verification of safety properties of programs to, first, proposing inductive assertions and, second, proving the validity of the resulting set of first-order verification conditions. We discuss the transition from verification conditions to verification constraints that occurs when the deductive method is applied to parameterized assertions instead of fixed expressi...

The development of formal models is often a key step when developing safety or mission critical software. In this setting it is vital to formally check and validate these formal models. We present PROB, a toolset for formal models expressed in the B method, which was developed using constraint logic programming technology. PROB allows fully automatic animation of B models, and can be used to sy...

For many random constraint satisfaction problems such as random satisfiability or random graph or hypergraph coloring, the best current estimates of the threshold for the existence of solutions are based on the first and the second moment method. However, in most cases these techniques do not yield matching upper and lower bounds. Sophisticated but non-rigorous arguments from statistical mechan...

Kakuro consists in filling a grid with integers that sum up to predefined values. Sums are predefined for each row and column and all integers have to be different in the same row or column. Kakuro can be modeled as a constraint satisfaction problem. Monte-Carlo methods can improve on traditional search methods for Kakuro. We show that a Nested Monte-Carlo Search at level 2 gives good results. ...

We show that for any odd k and any instance = of the Max-kXOR constraint satisfaction problem, there is an efficient algorithm that finds an assignment satisfying at least a 1 2 + Ω(1/ √ D) fraction of =’s constraints, where D is a bound on the number of constraints that each variable occurs in. This improves both qualitatively and quantitatively on the recent work of Farhi, Goldstone, and Gutm...

Huber, Krokhin, and Powell (2013) introduced a concept of skew bisubmodularity, as a generalization of bisubmodularity, in their complexity dichotomy theorem for valued constraint satisfaction problems over the three-value domain, and Huber and Krokhin (2014) showed the oracle tractability of minimization of skew-bisubmodular functions. Fujishige, Tanigawa, and Yoshida (2014) also showed a min-...

Constraint Satisfaction Problems can be solved using either iterative improvement or constructive search approaches. Iterative improvement techniques converge quicker than the constructive search techniques on large problems, but they have a propensity to converge to local optima. Therefore, a key research topic on iterative improvement search is the development of effective techniques for esca...

We address a location-allocation problem that requires deciding the location of a set of facilities, the allocation of customers to those facilities under facility capacity constraints, and the allocation of the customers to trucks at those facilities under per truck traveldistance constraints. We present a hybrid approach that combines integer programming and constraint programming using logic...

When solving constraint satisfaction problems (CSPs) with stochastic search algorithms (SSAs) using the standard penalty function, it is not possible to show that there is no solution for a problem instance. In this paper we present a hybrid function that can be generally used in conjunction with SSAs to prove unsolvability without changing the search algorithms drastically. We use eight state-...

In this paper, a novel method is proposed to detect salient regions in images. To measure pixel-level saliency, joint spatial-color constraint is defined, i.e., spatial constraint (SC), color double-opponent (CD) constraint and similarity distribution (SD) constraint. The SC constraint is designed to produce global contrast with ability to distinguish the difference between ‘‘center and surroun...