Begin, After, and Later: a Maximal Decidable Interval Temporal Logic

Davide Bresolin
(University of Verona, Verona, Italy)
Pietro Sala
(University of Verona, Verona, Italy)
Guido Sciavicco
(University of Murcia, Murcia, Spain)

Interval temporal logics (ITLs) are logics for reasoning about temporal statements expressed over intervals, i.e., periods of time. The most famous ITL studied so far is Halpern and Shoham's HS, which is the logic of the thirteen Allen's interval relations. Unfortunately, HS and most of its fragments have an undecidable satisfiability problem. This discouraged the research in this area until recently, when a number non-trivial decidable ITLs have been discovered.

This paper is a contribution towards the complete classification of all different fragments of HS. We consider different combinations of the interval relations Begins, After, Later and their inverses Abar, Bbar, and Lbar. We know from previous works that the combination ABBbarAbar is decidable only when finite domains are considered (and undecidable elsewhere), and that ABBbar is decidable over the natural numbers. We extend these results by showing that decidability of ABBar can be further extended to capture the language ABBbarLbar, which lays in between ABBar and ABBbarAbar, and that turns out to be maximal w.r.t decidability over strongly discrete linear orders (e.g. finite orders, the naturals, the integers). We also prove that the proposed decision procedure is optimal with respect to the complexity class.

In Angelo Montanari, Margherita Napoli and Mimmo Parente: Proceedings First Symposium on Games, Automata, Logic, and Formal Verification (GANDALF 2010), Minori (Amalfi Coast), Italy, 17-18th June 2010, Electronic Proceedings in Theoretical Computer Science 25, pp. 72–88.
Published: 9th June 2010.

ArXived at: http://dx.doi.org/10.4204/EPTCS.25.10 bibtex PDF

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