5 research outputs found
Modular Descriptions of Regular Functions
We discuss various formalisms to describe string-to-string transformations.
Many are based on automata and can be seen as operational descriptions,
allowing direct implementations when the input scanner is deterministic.
Alternatively, one may use more human friendly descriptions based on some
simple basic transformations (e.g., copy, duplicate, erase, reverse) and
various combinators such as function composition or extensions of regular
operations.Comment: preliminary version appeared in CAI 2019, LNCS 1154
Scenario realizability with constraint optimization
International audienceThis work considers implementation of requirements expressed as High-level Message Sequence Charts (HMSCs). All HMSCs are not implementable, but a particular subclass called local HMSCs can be implemented using a simple projection operation. This paper proposes a new technique to transform an arbitrary HMSC specification into a local HMSC, hence allowing implementation. We show that this transformation can be automated as a constraint optimization problem. The impact of modifications brought to the original specification can be minimized w.r.t. a cost function. The approach was evaluated on a large number of randomly generated HMSCs. The results show an average runtime of a few seconds, which demonstrates applicability of the technique
Optimal Zielonka-Type Construction of Deterministic Asynchronous Automata
International audienceAsynchronous automata are parallel compositions of finite- state processes synchronizing over shared variables. A deep theorem due to Zielonka says that every regular trace language can be represented by a deterministic asynchronous automaton. In this paper we improve the construction, in that the size of the obtained asynchronous automaton is polynomial in the size of a given DFA and simply exponential in the number of processes. We show that our construction is optimal within the class of automata produced by Zielonka-type constructions. In particular, we provide the first non trivial lower bound on the size of asynchronous automata
Realizability of Concurrent Recursive Programs
We define and study an automata model of concurrent recursive programs. An automaton consists of a finite number of pushdown systems running in parallel and communicating via shared actions. Actually, we combine multi-stack visibly pushdown automata and Zielonkaâs asynchronous automata towards a model with an undecidable emptiness problem. However, a reasonable restriction allows us to lift Zielonkaâs Theorem to this recursive setting and permits a logical characterization in terms of a suitable monadic second-order logic. Building on results from Mazurkiewicz trace theory and recent work by La Torre, Madhusudan, and Parlato, we thus develop a framework for the specification, synthesis, and verification of concurrent recursive processes