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In this paper, we present the Enfragmo system for specifying and solving combinatorial search problems. It supports natural specification of problems by providing users with a rich language, based on an extension of first order logic. Enfragmo takes as input a problem specification and a problem instance and produces a propositional CNF formula representing(More)
A Pseudo-Boolean (PB) constraint is a linear arithmetic constraint over Boolean variables. PB constraints are and widely used in declarative languages for expressing NP-hard search problems. While there are solvers for sets of PB constraints, there are also reasons to be interested in transforming these to propositional CNF formulas, and a number of methods(More)
A Pseudo-Boolean constraint is a linear constraint over Boolean variables. This kind of constraints has been widely used in expressing NP-complete problems. This paper introduces a new algorithm for translating Pseudo-Boolean constraints into CNF clauses. The CNF produced by the proposed encoding has small size, and we also characterize the constraints for(More)
Given a finite domain, grounding is the the process of creating a variablefree first-order formula equivalent to a first-order sentence. As the first-order sentences can be used to describe a combinatorial search problem, efficient grounding algorithms would help in solving such problems effectively and makes advanced solver technology (such as SAT)(More)
Grounding is the task of reducing a first order formula to ground formula that is equivalent on a given universe, and is important in many kinds of problem solving and reasoning systems. One method for grounding is based on an extension of the relational algebra, exploiting the fact that grounding over a given domain is similar to query answering. In this(More)
Today, Web interactions are frequently short, with an increasing number of responses carrying only control information and no data. On the other hand, with significant improvements in network hardware, many problems such as collision and packet loss are not as important as before. The most popular application layer protocol for the Web is the Hyper Text(More)
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