Almost Linear B\"uchi Automata

We introduce a new fragment of Linear temporal logic (LTL) called LIO and a new class of Buechi automata (BA) called Almost linear Buechi automata (ALBA). We provide effective translations between LIO and ALBA showing that the two formalisms are expressively equivalent. While standard translations of LTL into BA use some intermediate formalisms, the presented translation of LIO into ALBA is direct. As we expect applications of ALBA in model checking, we compare the expressiveness of ALBA with other classes of Buechi automata studied in this context and we indicate possible applications

Handling Conflicts in Depth-First Search for LTL Tableau to Debug Compliance Based Languages

Providing adequate tools to tackle the problem of inconsistent compliance rules is a critical research topic. This problem is of paramount importance to achieve automatic support for early declarative design and to support evolution of rules in contract-based or service-based systems. In this paper we investigate the problem of extracting temporal unsatisfiable cores in order to detect the inconsistent part of a specification. We extend conflict-driven SAT-solver to provide a new conflict-driven depth-first-search solver for temporal logic. We use this solver to compute LTL unsatisfiable cores without re-exploring the history of the solver.Comment: In Proceedings FLACOS 2011, arXiv:1109.239

Simple On-the-fly Automatic Verification of Linear Temporal Logic

peer reviewedWe present a tableau-based algorithm for obtaining an automaton from a temporal logic formula. The algorithm is geared towards being used in model checking in an “on-the-fly” fashion, that is the automaton can be constructed simultaneously with, and guided by, the generation of the model. In particular, it is possible to detect that a property does not hold by only constructing part of the model and of the automaton. The algorithm can also be used to check the validity of a temporal logic assertion. Although the general problem is PSPACE-complete, experiments show that our algorithm performs quite well on the temporal formulas typically encountered in verification. While basing linear-time temporal logic model-checking upon a transformation to automata is not new, the details of how to do this efficiently, and in “on-the-fly” fashion have never been given