Anytime Computation of Cautious Consequences in Answer Set Programming

Query answering in Answer Set Programming (ASP) is usually solved by computing (a subset of) the cautious consequences of a logic program. This task is computationally very hard, and there are programs for which computing cautious consequences is not viable in reasonable time. However, current ASP solvers produce the (whole) set of cautious consequences only at the end of their computation. This paper reports on strategies for computing cautious consequences, also introducing anytime algorithms able to produce sound answers during the computation.Comment: To appear in Theory and Practice of Logic Programmin

I fondamenti teologici del pensiero politico agostiniano: le virtù teologali dello statista come ponte tra le due città

Augustine’s approach to politics and, hence, to political ethics, begins with consideration of the human being or “soul” and reaches its highpoint in the ideal of a Christian statesman, not in an ideal political order. Augustine offers no theory concerning the relationship between the church and the political order. On the other hand, the paper contends that his concept of the ideal statesman provides the elusive bridge in his thought between ecclesia and res publica. Augustine’s ideal of the Christian statesman is framed against the background of his reflections concerning Christ, because, in his view, Christ alone mediates true virtue to the soul, and therefore to the statesman. Augustine thus takes up the task in the City of God and in his letters to public officials to deconstruct all other accounts of political virtue – philosophical and religious – on the grounds that real virtue is to be understood exclusively as Christ’s virtue acting through the human soul. This principle is what characterizes the radical originality of Augustine’s approach to political ethics

Constraints, Lazy Constraints, or Propagators in ASP Solving: An Empirical Analysis

Answer Set Programming (ASP) is a well-established declarative paradigm. One of the successes of ASP is the availability of efficient systems. State-of-the-art systems are based on the ground+solve approach. In some applications this approach is infeasible because the grounding of one or few constraints is expensive. In this paper, we systematically compare alternative strategies to avoid the instantiation of problematic constraints, that are based on custom extensions of the solver. Results on real and synthetic benchmarks highlight some strengths and weaknesses of the different strategies. (Under consideration for acceptance in TPLP, ICLP 2017 Special Issue.)Comment: Paper presented at the 33nd International Conference on Logic Programming (ICLP 2017), Melbourne, Australia, August 28 to September 1, 2017. 16 page

A Tool for Encoding Controlled Natural Language Specifications as ASP Rules.

Answer Set Programming (ASP) is a popular declarative programming language for solving hard combinatorial problems. Albeit ASP has been widely adopted in both academic and industrial contexts, it might be difficult for people who are not familiar with logic programming conventions to use it. In this paper, we propose a translation of English sentences expressed in a controlled natural language (CNL) form into ASP. In particular, we first provide a definition of the type of sentences allowed by our CNL and their translation as ASP rules, and then exemplify the usage of CNL for the specification of well-known combinatorial problems