Extending Coinductive Logic Programming with Co-Facts

Davide Ancona
(DIBRIS, University of Genova )
Francesco Dagnino
(DIBRIS, University of Genova )
Elena Zucca
(DIBRIS, University of Genova )

We introduce a generalized logic programming paradigm where programs, consisting of facts and rules with the usual syntax, can be enriched by co-facts, which syntactically resemble facts but have a special meaning. As in coinductive logic programming, interpretations are subsets of the complete Herbrand basis, including infinite terms. However, the intended meaning (declarative semantics) of a program is a fixed point which is not necessarily the least, nor the greatest one, but is determined by co-facts. In this way, it is possible to express predicates on non well-founded structures, such as infinite lists and graphs, for which the coinductive interpretation would be not precise enough. Moreover, this paradigm nicely subsumes standard (inductive) and coinductive logic programming, since both can be expressed by a particular choice of co-facts, hence inductive and coinductive predicates can coexist in the same program. We illustrate the paradigm by examples, and provide declarative and operational semantics, proving the correctness of the latter. Finally, we describe a prototype meta-interpreter.

In Ekaterina Komendantskaya and John Power: Proceedings of the First Workshop on Coalgebra, Horn Clause Logic Programming and Types (CoALP-Ty'16), Edinburgh, UK, 28-29 November 2016, Electronic Proceedings in Theoretical Computer Science 258, pp. 1–18.
Published: 13th September 2017.

ArXived at: http://dx.doi.org/10.4204/EPTCS.258.1 bibtex PDF
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