96 research outputs found
Commutative Languages and their Composition by Consensual Methods
Commutative languages with the semilinear property (SLIP) can be naturally
recognized by real-time NLOG-SPACE multi-counter machines. We show that unions
and concatenations of such languages can be similarly recognized, relying on --
and further developing, our recent results on the family of consensually
regular (CREG) languages. A CREG language is defined by a regular language on
the alphabet that includes the terminal alphabet and its marked copy. New
conditions, for ensuring that the union or concatenation of CREG languages is
closed, are presented and applied to the commutative SLIP languages. The paper
contributes to the knowledge of the CREG family, and introduces novel
techniques for language composition, based on arithmetic congruences that act
as language signatures. Open problems are listed.Comment: In Proceedings AFL 2014, arXiv:1405.527
Dense-choice Counter Machines revisited
This paper clarifies the picture about Dense-choice Counter Machines, which
have been less studied than (discrete) Counter Machines. We revisit the
definition of "Dense Counter Machines" so that it now extends (discrete)
Counter Machines, and we provide new undecidability and decidability results.
Using the first-order additive mixed theory of reals and integers, we give a
logical characterization of the sets of configurations reachable by
reversal-bounded Dense-choice Counter Machines
Deciding the Satisfiability of MITL Specifications
In this paper we present a satisfiability-preserving reduction from MITL
interpreted over finitely-variable continuous behaviors to Constraint LTL over
clocks, a variant of CLTL that is decidable, and for which an SMT-based bounded
satisfiability checker is available. The result is a new complete and effective
decision procedure for MITL. Although decision procedures for MITL already
exist, the automata-based techniques they employ appear to be very difficult to
realize in practice, and, to the best of our knowledge, no implementation
currently exists for them. A prototype tool for MITL based on the encoding
presented here has, instead, been implemented and is publicly available.Comment: In Proceedings GandALF 2013, arXiv:1307.416
from regular to strictly locally testable languages
Comment: In Proceedings WORDS 2011, arXiv:1108.341
Bounded Reachability for Temporal Logic over Constraint Systems
We present CLTLB(D), an extension of PLTLB (PLTL with both past and future
operators) augmented with atomic formulae built over a constraint system D.
Even for decidable constraint systems, satisfiability and Model Checking
problem of such logic can be undecidable. We introduce suitable restrictions
and assumptions that are shown to make the satisfiability problem for the
extended logic decidable. Moreover for a large class of constraint systems we
propose an encoding that realize an effective decision procedure for the
Bounded Reachability problem
Constraint LTL Satisfiability Checking without Automata
This paper introduces a novel technique to decide the satisfiability of
formulae written in the language of Linear Temporal Logic with Both future and
past operators and atomic formulae belonging to constraint system D (CLTLB(D)
for short). The technique is based on the concept of bounded satisfiability,
and hinges on an encoding of CLTLB(D) formulae into QF-EUD, the theory of
quantifier-free equality and uninterpreted functions combined with D. Similarly
to standard LTL, where bounded model-checking and SAT-solvers can be used as an
alternative to automata-theoretic approaches to model-checking, our approach
allows users to solve the satisfiability problem for CLTLB(D) formulae through
SMT-solving techniques, rather than by checking the emptiness of the language
of a suitable automaton A_{\phi}. The technique is effective, and it has been
implemented in our Zot formal verification tool.Comment: 39 page
- …