Formal language

About: Formal language is a research topic. Over the lifetime, 5763 publications have been published within this topic receiving 154114 citations.

Analysis support for TADL2 timing constraints on EAST-ADL models

Abstract: It is critical to analyze characteristics of real-time embedded systems, such as timing behavior, early in the development. In the automotive domain, EAST-ADL is a concrete example of the model-based approach for the architectural modeling of real-time systems. The Timing Augmented Description Language v2 (TADL2) allows for the specification of timing constraints on top of EAST-ADL models. In this paper we propose a formal validation & verification methodology for timing behaviors given with TADL2. The formal semantics of the timing constraints is given as a mapping to the Clock Constraint Specification Language (CCSL), a formal language that implements the MARTE Time Model. Based on such a mapping, the validation is carried out by the simulation of TADL2 specifications. The simulation allows for a rapid prototyping of TADL2 specifications. The verification is performed based on a TADL2 mapping to timed automata modeling using the Uppaal model-checker. The whole process is illustrated on a Brake-By-Wire application.

Characterising REGEX languages by regular languages equipped with factor-referencing

Abstract: A (factor-)reference in a word is a special symbol that refers to another factor in the same word; a reference is dereferenced by substituting it with the referenced factor. We introduce and investigate the class ref-REG of all languages that can be obtained by taking a regular language R and then dereferencing all possible references in the words of R. We show that ref-REG coincides with the class of languages defined by regular expressions as they exist in modern programming languages like Perl, Python, Java, etc. (often called REGEX languages).

State complexity of basic operations on suffix-free regular languages

Abstract: We investigate the state complexity of basic operations for suffix-free regular languages. The state complexity of an operation for regular languages is the number of states that are necessary and sufficient in the worst-case for the minimal deterministic finite-state automaton that accepts the language obtained from the operation. We establish the precise state complexity of catenation, Kleene star, reversal and the Boolean operations for suffix-free regular languages.

International contracting-a formal language approach

Abstract: A model of international electronic contracting is proposed whereby parties express contractual terms and conditions in a restricted form of their native language. This is parsed into a formalized language, called Candid, for transmission over the network. At the receiving end, the Candid representation is rephrased into a similarly restricted form of the receiver's native language. An operating prototype is presented with examples in English, German, and Portuguese. Further extensions are discussed. >

Valuations and Unambiguity of Languages, with Applications to Fractal Geometry

Abstract: Valuations — morphisms from (Σ*·λ) to ((0, ∞),·,1) —are a simple generalization of Bernoulli morphisms (distributions, measures) as introduced in [12, 20, 6, 4, 5, 21]. This paper shows that valuations are not only useful within the theory of codes, but also when dealing with ambiguity, especially in regular expressions and contextfree grammars, or for defining outer measures on the space of ω-words which are of some importance for the theory of fractals. These connections yield new formulae to determine the Hausdorff dimension of fractal sets (especially in Euclidean spaces) defined via regular expressions and contextfree grammars.