3,724 research outputs found
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
Bounded LTL Model Checking with Stable Models
In this paper bounded model checking of asynchronous concurrent systems is
introduced as a promising application area for answer set programming. As the
model of asynchronous systems a generalisation of communicating automata,
1-safe Petri nets, are used. It is shown how a 1-safe Petri net and a
requirement on the behaviour of the net can be translated into a logic program
such that the bounded model checking problem for the net can be solved by
computing stable models of the corresponding program. The use of the stable
model semantics leads to compact encodings of bounded reachability and deadlock
detection tasks as well as the more general problem of bounded model checking
of linear temporal logic. Correctness proofs of the devised translations are
given, and some experimental results using the translation and the Smodels
system are presented.Comment: 32 pages, to appear in Theory and Practice of Logic Programmin
Weak Singular Hybrid Automata
The framework of Hybrid automata, introduced by Alur, Courcourbetis,
Henzinger, and Ho, provides a formal modeling and analysis environment to
analyze the interaction between the discrete and the continuous parts of
cyber-physical systems. Hybrid automata can be considered as generalizations of
finite state automata augmented with a finite set of real-valued variables
whose dynamics in each state is governed by a system of ordinary differential
equations. Moreover, the discrete transitions of hybrid automata are guarded by
constraints over the values of these real-valued variables, and enable
discontinuous jumps in the evolution of these variables. Singular hybrid
automata are a subclass of hybrid automata where dynamics is specified by
state-dependent constant vectors. Henzinger, Kopke, Puri, and Varaiya showed
that for even very restricted subclasses of singular hybrid automata, the
fundamental verification questions, like reachability and schedulability, are
undecidable. In this paper we present \emph{weak singular hybrid automata}
(WSHA), a previously unexplored subclass of singular hybrid automata, and show
the decidability (and the exact complexity) of various verification questions
for this class including reachability (NP-Complete) and LTL model-checking
(PSPACE-Complete). We further show that extending WSHA with a single
unrestricted clock or extending WSHA with unrestricted variable updates lead to
undecidability of reachability problem
Generalization Strategies for the Verification of Infinite State Systems
We present a method for the automated verification of temporal properties of
infinite state systems. Our verification method is based on the specialization
of constraint logic programs (CLP) and works in two phases: (1) in the first
phase, a CLP specification of an infinite state system is specialized with
respect to the initial state of the system and the temporal property to be
verified, and (2) in the second phase, the specialized program is evaluated by
using a bottom-up strategy. The effectiveness of the method strongly depends on
the generalization strategy which is applied during the program specialization
phase. We consider several generalization strategies obtained by combining
techniques already known in the field of program analysis and program
transformation, and we also introduce some new strategies. Then, through many
verification experiments, we evaluate the effectiveness of the generalization
strategies we have considered. Finally, we compare the implementation of our
specialization-based verification method to other constraint-based model
checking tools. The experimental results show that our method is competitive
with the methods used by those other tools. To appear in Theory and Practice of
Logic Programming (TPLP).Comment: 24 pages, 2 figures, 5 table
SMT-based Verification of LTL Specifications with Integer Constraints and its Application to Runtime Checking of Service Substitutability
An important problem that arises during the execution of service-based
applications concerns the ability to determine whether a running service can be
substituted with one with a different interface, for example if the former is
no longer available. Standard Bounded Model Checking techniques can be used to
perform this check, but they must be able to provide answers very quickly, lest
the check hampers the operativeness of the application, instead of aiding it.
The problem becomes even more complex when conversational services are
considered, i.e., services that expose operations that have Input/Output data
dependencies among them. In this paper we introduce a formal verification
technique for an extension of Linear Temporal Logic that allows users to
include in formulae constraints on integer variables. This technique applied to
the substitutability problem for conversational services is shown to be
considerably faster and with smaller memory footprint than existing ones
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