arXiv subjects

Francesco Ricca

Publications and source records attributed to Francesco Ricca.

41 records · Page 3Linked to original sources

arXiv2012

The third open Answer Set Programming competition

Answer Set Programming (ASP) is a well-established paradigm of declarative programming in close relationship with other declarative formalisms such as SAT Modulo Theories, Constraint Handling Rules, FO(.), PDDL and many others. Since its first informal editions, ASP systems have been compared in the now well-established ASP Competition. The Third (Open) ASP Competition, as the sequel to the ASP Competitions Series held at the University of Potsdam in Germany (2006-2007) and at the University of Leuven in Belgium in 2009, took place at the University of Calabria (Italy) in the first half of 2011. Participants competed on a pre-selected collection of benchmark problems, taken from a variety of domains as well as real world applications. The Competition ran on two tracks: the Model and Solve (M&S) Track, based on an open problem encoding, and open language, and open to any kind of system based on a declarative specification paradigm; and the System Track, run on the basis of fixed, public problem encodings, written in a standard ASP language. This paper discusses the format of the Competition and the rationale behind it, then reports the results for both tracks. Comparison with the second ASP competition and state-of-the-art solutions for some of the benchmark domains is eventually discussed. To appear in Theory and Practice of Logic Programming (TPLP).

cs.AI↗

arXiv2011

Parallel Instantiation of ASP Programs: Techniques and Experiments

Answer Set Programming (ASP) is a powerful logic-based programming language, which is enjoying increasing interest within the scientific community and (very recently) in industry. The evaluation of ASP programs is traditionally carried out in two steps. At the first step an input program P undergoes the so-called instantiation (or grounding) process, which produces a program P' semantically equivalent to P, but not containing any variable; in turn, P' is evaluated by using a backtracking search algorithm in the second step. It is well-known that instantiation is important for the efficiency of the whole evaluation, might become a bottleneck in common situations, is crucial in several realworld applications, and is particularly relevant when huge input data has to be dealt with. At the time of this writing, the available instantiator modules are not able to exploit satisfactorily the latest hardware, featuring multi-core/multi-processor SMP (Symmetric MultiProcessing) technologies. This paper presents some parallel instantiation techniques, including load-balancing and granularity control heuristics, which allow for the effective exploitation of the processing power offered by modern SMP machines. This is confirmed by an extensive experimental analysis herein reported. To appear in Theory and Practice of Logic Programming (TPLP). KEYWORDS: Answer Set Programming, Instantiation, Parallelism, Heuristics

cs.PL↗

arXiv2011

Consistent Query Answering via ASP from Different Perspectives: Theory and Practice

A data integration system provides transparent access to different data sources by suitably combining their data, and providing the user with a unified view of them, called global schema. However, source data are generally not under the control of the data integration process, thus integrated data may violate global integrity constraints even in presence of locally-consistent data sources. In this scenario, it may be anyway interesting to retrieve as much consistent information as possible. The process of answering user queries under global constraint violations is called consistent query answering (CQA). Several notions of CQA have been proposed, e.g., depending on whether integrated information is assumed to be sound, complete, exact or a variant of them. This paper provides a contribution in this setting: it uniforms solutions coming from different perspectives under a common ASP-based core, and provides query-driven optimizations designed for isolating and eliminating inefficiencies of the general approach for computing consistent answers. Moreover, the paper introduces some new theoretical results enriching existing knowledge on decidability and complexity of the considered problems. The effectiveness of the approach is evidenced by experimental results. To appear in Theory and Practice of Logic Programming (TPLP).

cs.DB↗

arXiv2011

Unit Testing in ASPIDE

Answer Set Programming (ASP) is a declarative logic programming formalism, which is employed nowadays in both academic and industrial real-world applications. Although some tools for supporting the development of ASP programs have been proposed in the last few years, the crucial task of testing ASP programs received less attention, and is an Achilles' heel of the available programming environments. In this paper we present a language for specifying and running unit tests on ASP programs. The testing language has been implemented in ASPIDE, a comprehensive IDE for ASP, which supports the entire life-cycle of ASP development with a collection of user-friendly graphical tools for program composition, testing, debugging, profiling, solver execution configuration, and output-handling.

cs.PL↗

arXiv2011

Team-building with Answer Set Programming in the Gioia-Tauro Seaport

(To appear in Theory and Practice of Logic Programming (TPLP).) The seaport of Gioia Tauro is the largest transshipment terminal of the Mediterranean coast. A crucial management task for the companies operating in the seaport is team building: the problem of properly allocating the available personnel for serving the incoming ships. Teams have to be carefully arranged in order to meet several constraints, such as allocation of the employees with the appropriate skills, fair distribution of the working load, and turnover of the heavy/dangerous roles. This makes team building a hard and expensive task requiring several hours per day of manual preparation. In this paper we present a system based on Answer Set Programming (ASP) for the automatic generation of the teams of employees in the seaport of Gioia Tauro. The system is currently exploited in the Gioia Tauro seaport by ICO BLG, a company specialized in automobile logistics.

cs.LO↗