ASP at Work: Spin-off and Applications of the DLV System ⋆ Giovanni Grasso, Nicola Leone, Marco Manna, and Francesco Ricca Department of Mathematics, University of Calabria, Italy {grasso,leone,manna,ricca}@mat.unical.it Abstract. Answer Set Programming (ASP) is a declarative language for knowledge representation and reasoning. After its proposal, in a sem- inal paper by Michael Gelfond and Vladimir Lifschitz dated in 1988, ASP has been the subject of a broad theoretical research-work, ranging from linguistic extensions and semantic properties to evaluation algorithm and optimization techniques. Later on, the availability of a number of effi- cient systems made ASP a powerful tool for the fast development of knowledge-based applications. In this paper, we report on the ongoing effort aimed at the industrial exploitation of DLV– one of the most pop- ular ASP systems – in the area of Knowledge Management. Two spin-off companies of University of Calabria are involved in such an exploitation: Dlvsystem Srl and Exeura Srl. They have specialized DLV into some Knowledge Management products for Text Classification, Information Extraction, and Ontology Representation and Reasoning, which have al- lowed to develop a number of successful real-world applications. Keywords: ASP, DLV System, Knowledge Management, Applications. 1 Introduction Answer Set Programming (ASP) is a powerful logic programming language hav- ing its roots in the seminal papers [38,39] by Michael Gelfond and Vladimir Lif- schitz. ASP is a purely declarative and expressive language that can represent, in its general form allowing for disjunction in rule heads [50] and nonmonotonic negation in rule bodies, every problem in the complexity classes Σ P 2 and Π P 2 (under brave and cautious reasoning, respectively) [27]. The comparatively-high expressive power of ASP comes with the capability of providing, in a compact- yet-elegant way, ready-to-execute formal specifications of complex problems. In- deed, the ASP encoding of a large variety of problems is very concise, simple, and elegant [5,26,36,23]. As an example, consider the well-known NP-complete problem 3-coloring: given an undirected graph G =(V,E), assign each vertex one of three colors -say, red, green, or blue- such that adjacent vertices alwayshave distinct colors. 3-coloring can be encoded in ASP as follows: ⋆ This work was partially supported by the Regione Calabria and EU under POR Calabria FESR 2007-2013 within the PIA project of TopClass Srl. M. Balduccini and T.C. Son (Eds.): Gelfond Festschrift, LNAI 6565, pp. 432–451, 2011. c  Springer-Verlag Berlin Heidelberg 2011