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The ConflictDriven Answer Set Solver clasp: Progress Report
"... Abstract. We summarize the salient features of the current version of the answer set solver clasp, focusing on the progress made since version RC4 of clasp. Apart from enhanced preprocessing and searchsupporting techniques, a particular emphasis lies on advanced reasoning modes, such as cautious an ..."
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Cited by 17 (2 self)
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Abstract. We summarize the salient features of the current version of the answer set solver clasp, focusing on the progress made since version RC4 of clasp. Apart from enhanced preprocessing and searchsupporting techniques, a particular emphasis lies on advanced reasoning modes, such as cautious and brave reasoning, optimization, solution projection, and incremental solving. 1
Detecting Inconsistencies in Large Biological Networks with Answer Set Programming ⋆
"... Abstract. We introduce an approach to detecting inconsistencies in large biological networks by using Answer Set Programming. To this end, we build upon a recently proposed notion of consistency between biochemical/genetic reactions and highthroughput profiles of cell activity. We then present an a ..."
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Cited by 15 (10 self)
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Abstract. We introduce an approach to detecting inconsistencies in large biological networks by using Answer Set Programming. To this end, we build upon a recently proposed notion of consistency between biochemical/genetic reactions and highthroughput profiles of cell activity. We then present an approach based on Answer Set Programming to check the consistency of largescale data sets. Moreover, we extend this methodology to provide explanations for inconsistencies in the data by determining minimal representations of conflicts. In practice, this can be used to identify unreliable data or to indicate missing reactions. 1
A Translational Approach to Constraint Answer Set Solving
 UNDER CONSIDERATION FOR PUBLICATION IN THEORY AND PRACTICE OF LOGIC PROGRAMMING
, 2010
"... We present a new approach to enhancing Answer Set Programming (ASP) with Constraint Processing techniques which allows for solving interesting Constraint Satisfaction Problems in ASP. We show how constraints on finite domains can be decomposed into logic programs such that unitpropagation achieves ..."
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Cited by 13 (5 self)
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We present a new approach to enhancing Answer Set Programming (ASP) with Constraint Processing techniques which allows for solving interesting Constraint Satisfaction Problems in ASP. We show how constraints on finite domains can be decomposed into logic programs such that unitpropagation achieves arc, bound or range consistency. Experiments with our encodings demonstrate their computational impact.
Extremely Complex 4Colored RectangleFree Grids: Solution of Open MultipleValued Problems. Accepted for presentation on the
 IEEE 42nd International Symposium on MultipleValued Logic (ISMVL 2012) May 1416
, 2012
"... Abstract—This paper aims at the rectanglefree coloring of grids using four colors. It has been proven in a well developed theory that there is an upper bound of rectanglefree 4colorable grids as well as a lower bound of grids for which no rectanglefree color pattern of four colors exist. Between ..."
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Cited by 6 (5 self)
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Abstract—This paper aims at the rectanglefree coloring of grids using four colors. It has been proven in a well developed theory that there is an upper bound of rectanglefree 4colorable grids as well as a lower bound of grids for which no rectanglefree color pattern of four colors exist. Between these tight bounds the grids of the size 17×17, 17×18, 18×17, and 18×18 are located for which it is not known until now whether a rectanglefree coloring by four colors exists. We present in this paper an approach that solves all these open problems. From another point of view this paper aims at the solution of a multiplevalued problem having an extremely high complexity. There are 1.16798 ∗ 10 195 different grids of four colors. It must be detected whether at least one of this hardly imaginable large number of patterns satisfies strong additional conditions. In order to solve this highly complex problem, several approaches were taken into account to find out properties of the problem which finally allowed us to calculate the solution. Keywordsfourvalued coloring, rectanglefree grid, Boolean equation, SATsolver, XBOOLE. I.
A.: Metainterpretive learning: application to grammatical inference. Machine Learning (forthcoming
"... Abstract. Despite early interest Predicate Invention has lately been underexplored within ILP. We develop a framework in which predicate invention and recursive generalisations are implemented using abduction with respect to a metainterpreter. The approach is based on a previously unexplored case ..."
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Cited by 5 (4 self)
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Abstract. Despite early interest Predicate Invention has lately been underexplored within ILP. We develop a framework in which predicate invention and recursive generalisations are implemented using abduction with respect to a metainterpreter. The approach is based on a previously unexplored case of Inverse Entailment for Grammatical Inference of Regular languages. Every abduced grammar H is represented by a conjunction of existentially quantified atomic formulae. Thus ¬H is a universally quantified clause representing a denial. The hypothesis space of solutions for ¬H can be ordered by θsubsumption. We show that the representation can be mapped to a fragment of HigherOrder Datalog in which atomic formulae in H are projections of firstorder definite clause grammar rules and the existentially quantified variables are projections of firstorder predicate symbols. This allows predicate invention to be effected by the introduction of firstorder variables. This application of abduction to conduct predicate invention is related to that of previous work by Inoue and Furukawa. We show that the approach is sufficiently flexible to support learning of ContextFree grammars from positive and negative example, a problem shown to be theoretically possible by E.M. Gold in the 1960s, though to the authors ’ knowledge, not previously demonstrated within Grammatical Inference. We describe the implementation of Metagol R and Metagol CF for learning Regular and ContextFree grammars respectively. Experiments indicate that on
Utilization of Permutation Classes for Solving Extremely Complex 4Colorable Rectanglefree Grids Submitted to
 the 2012 International Conference on Systems and Informatics (ICSAI
"... Abstract—This paper aims at the rectanglefree coloring of grids using four colors. It has been proven that there are bounds for the size of rectanglefree fourcolorable grids outside of these values the grids cannot be colored. For the grids of the size 17×17, 17×18, 18×17, and 18×18 it is not ye ..."
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Cited by 4 (4 self)
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Abstract—This paper aims at the rectanglefree coloring of grids using four colors. It has been proven that there are bounds for the size of rectanglefree fourcolorable grids outside of these values the grids cannot be colored. For the grids of the size 17×17, 17×18, 18×17, and 18×18 it is not yet known whether rectanglefree colorings by four colors exist. A necessary condition for rectanglefree fourcolorable grids of the size 18×18 is that at least one fourth of the grid elements can be colored by a single color without violating the rectanglefree condition. This simplified task requires to evaluate 2 18∗18 = 2 324 = 3.41758 ∗10 97 assignments to the grid elements whether at least 18∗18/4 = 81 elements can be colored by the same color without violating the rectanglefree condition. We present in this paper an approach that allows to calculate such extremely large sets of assignments using the restricted memory space of a normal PC and a short period of time. The key to our solution is the utilization of permutation classes. However, even a single permutation class consists of such an extreme number of assignments that it can neither be stored nor enumerated. Hence, it is the main aim of this paper to find a way that allows us to decide whether two grid assignments are members of the same permutation class under these extreme conditions. On the basis of such an approach we are going to answer the question whether an extremely rare fourcolorable rectanglefree grid G18,18 can exist within the huge amount of 4 324 = 1.16798∗ 10 195 possible fourcolorings of such grids. I.
Simple Random Logic Programs
"... Abstract. We consider random logic programs with twoliteral rules and study their properties. In particular, we obtain results on the probability that random “sparse ” and “dense ” programs with twoliteral rules have answer sets. We study experimentally how hard it is to compute answer sets of suc ..."
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Cited by 3 (1 self)
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Abstract. We consider random logic programs with twoliteral rules and study their properties. In particular, we obtain results on the probability that random “sparse ” and “dense ” programs with twoliteral rules have answer sets. We study experimentally how hard it is to compute answer sets of such programs. For programs that are constraintfree and purely negative we show that the easyhardeasy pattern emerges. We provide arguments to explain that behavior. We also show that the hardness of programs from the hard region grows quickly with the number of atoms. Our results point to the importance of purely negative constraintfree programs for the development of ASP solvers. 1
A Versatile Intermediate Language for Answer Set Programming
"... The attractiveness of Answer Set Programming (ASP) and related paradigms for declarative problem solving is considerably due to the availability of highly efficient yet easytouse implementations. A major driving force for the development and improvement of tools are standardized problem representa ..."
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Cited by 2 (1 self)
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The attractiveness of Answer Set Programming (ASP) and related paradigms for declarative problem solving is considerably due to the availability of highly efficient yet easytouse implementations. A major driving force for the development and improvement of tools are standardized problem representations, for several reasons. First, they relieve developers from the burden of inventing their own input formats. Second, they establish interoperability between separate tools, allowing users to easily compare and exchange them without extensively converting their problem representations. Third, they facilitate the acquisition of problem descriptions from distinct sources, which is useful for benchmarking and assessment purposes. Historically, however, standards for representing logic programs, serving as inputs to ASP systems, were mainly dictated by the few available tools. In fact, there currently are two quasi standards, namely, the formats used by lparse and dlv, incompatible with each other. As a first step towards overcoming this deficiency, this work proposes an intermediate format for ground logic programs, intended for the representation of inputs to ASP solvers. The format is not designed to be a primary input language, given that ASP systems usually deploy a second component, called a grounder, to deal with the inputs provided by users. In view of this, our format is situated intermediate a grounder and a solver, guided by the example of grounder lparse and solver smodels, the latter marking the first among nowadays a variety of solvers processing the output of lparse. However, the output format of lparse has some decisive drawbacks, namely, its restrictive range and limited extensibility. We thus propose a new intermediate language, where our major design goals are flexibility in problem representation and easy extensibility to new language constructs.