Is lazy abstraction a decision procedure for broadcast protocols?

Lazy abstraction builds up an abstract reachability tree by locally refining abstractions in order to eliminate spurious counterexamples in smaller and smaller subtrees. The method has proven useful to verify systems code. It is still open how good the method is as a decision procedure, i.e., whether the method terminates for already known decidable verification problems. In this paper, we answer the question positively for broadcast protocols and other infinite-state models in the class of so-called well-structured systems. This extends an existing result on systems with a finite bisimulation quotient

On recognizable timed languages

Abstract. In this work we generalize the fundamental notion of recognizability from untimed to timed languages. The essence of our definition is the existence of a right-morphism from the monoid of timed words into a bounded subset of itself. We show that the recognizable languages are exactly those accepted by deterministic timed automata and argue that this is, perhaps, the right class of timed languages, and that the closure of untimed regular languages under projection is a positive accident that cannot be expected to hold beyond the finite-state case.

SALT - Structured Assertion Language for Temporal Logic

This paper presents Salt. Salt is a general purpose specification and assertion language developed for creating concise temporal specifications to be used in industrial verification environments. It incorporates ideas of existing approaches, such as specification patterns, but also provides nested scopes, exceptions, support for regular expressions and real-time. The latter is needed in particular for verification tasks to do with reactive systems imposing strict execution times and deadlines

From MITL to timed automata

We show how to transform formulae written in the real-time temporal logic MITL into timed automata that recognize their satisfying models. This compositional construction is much simpler than previously known and can be easily implemented

Asynchronously Communicating Visibly Pushdown Systems

Abstract. We introduce an automata-based formal model suitable for specifying, modeling, analyzing, and verifying asynchronous task-based and message-passing programs. Our model consists of visibly pushdown automata communicating over unbounded reliable point-to-point firstin-first-out queues. Such a combination unifies two branches of research, one focused on task-based models, and the other on models of messagepassing programs. Our model generalizes previously proposed models that have decidable reachability in several ways. Unlike task-based models of asynchronous programs, our model allows sending and receiving of messages even when stacks are not empty, without imposing restrictions on the number of context-switches or communication topology. Our model also generalizes the well-known communicating finite-state machines with recognizable channel property allowing (1) individual components to be visibly pushdown automata, which are more suitable for modeling (possibly recursive) programs, (2) the set of words (i.e., languages) of messages on queues to form a visibly pushdown language, which permits modeling of remote procedure calls and simple forms of counting, and (3) the relations formed by tuples of such languages to be synchronized, which permits modeling of complex interactions among processes. In spite of these generalizations, we prove that the composite configuration and control-state reachability are still decidable for our model.