4,380 research outputs found
A Complete Axiomatisation of a Fragment of Language Algebra
We consider algebras of languages over the signature of reversible Kleene lattices, that is the regular operations (empty and unit languages, union, concatenation and Kleene star) together with intersection and mirror image. We provide a complete set of axioms for the equational theory of these algebras. This proof was developed in the proof assistant Coq
Facilitating modular property-preserving extensions of programming languages
We will explore an approach to modular programming language descriptions and extensions in a denotational style.
Based on a language core, language features are added stepwise on the core. Language features can be described
separated from each other in a self-contained, orthogonal way. We present an extension semantics framework consisting
of mechanisms to adapt semantics of a basic language to new structural requirements in an extended language
preserving the behaviour of programs of the basic language. Common templates of extension are provided. These
can be collected in extension libraries accessible to and extendible by language designers. Mechanisms to extend
these libraries are provided. A notation for describing language features embedding these semantics extensions is
presented
Two Decades of Maude
This paper is a tribute to JosĆ© Meseguer, from the rest of us in the Maude team, reviewing the past, the present, and the future of the language and system with which we have been working for around two decades under his leadership. After reviewing the origins and the language's main features, we present the latest additions to the language and some features currently under development. This paper is not an introduction to Maude, and some familiarity with it and with rewriting logic are indeed assumed.Universidad de MĆ”laga. Campus de Excelencia Internacional AndalucĆa Tech
Fair Simulation for Nondeterministic and Probabilistic Buechi Automata: a Coalgebraic Perspective
Notions of simulation, among other uses, provide a computationally tractable
and sound (but not necessarily complete) proof method for language inclusion.
They have been comprehensively studied by Lynch and Vaandrager for
nondeterministic and timed systems; for B\"{u}chi automata the notion of fair
simulation has been introduced by Henzinger, Kupferman and Rajamani. We
contribute to a generalization of fair simulation in two different directions:
one for nondeterministic tree automata previously studied by Bomhard; and the
other for probabilistic word automata with finite state spaces, both under the
B\"{u}chi acceptance condition. The former nondeterministic definition is
formulated in terms of systems of fixed-point equations, hence is readily
translated to parity games and is then amenable to Jurdzi\'{n}ski's algorithm;
the latter probabilistic definition bears a strong ranking-function flavor.
These two different-looking definitions are derived from one source, namely our
coalgebraic modeling of B\"{u}chi automata. Based on these coalgebraic
observations, we also prove their soundness: a simulation indeed witnesses
language inclusion
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