Formal language

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

Reduction and slicing of hierarchical state machines

Abstract: Formal specification languages are often criticized for being difficult to understand, difficult to use, and unacceptable by software practitioners. Notations based on state machines, such as, Statecharts, Requirements State Machine Language (RSML), and SCR, are suitable for modeling of embedded systems and eliminate many of the main drawbacks of formal specification languages. Although a specification language can help eliminate accidental complexity, the inherent complexity of many of today's systems inevitably leads to large and complex specifications. Thus, there is a need for mechanisms to simplify a formal specification and present information to analysts and reviewers in digestible chunks.

Formal properties of XML grammars and languages

Abstract: We consider XML documents described by a document type definition (DTD). An XML-grammar is a formal grammar that captures the syntactic features of a DTD. We investigate properties of this family of grammars. We show that every XML-language basically has a unique XML-grammar. We give two characterizations of languages generated by XML-grammars, one is set-theoretic, the other is by a kind of saturation property. We investigate decidability problems and prove that some properties that are undecidable for general context-free languages become decidable for XML-languages. We also characterize those XML-grammars that generate regular XML-languages.

Formal languages for integer programming modeling of shift scheduling problems

Abstract: This paper approaches the problem of modeling optimization problems containing substructures involving constraints on sequences of decision variables. Such constraints can be very complex to express with Mixed Integer Programming (MIP). We suggest an approach inspired by global constraints used in Constraint Programming (CP) to exploit formal languages for the modeling of such substructures with MIP. More precisely, we first suggest a way to use automata, as the CP regular constraint does, to express allowed patterns for the values taken by the constrained sequence of variables. Secondly, we present how context-free grammars can contribute to formulate constraints on sequences of variables in a MIP model. Experimental results on both approaches show that they facilitate the modeling, but also give models easier to solve by MIP solvers compared to compact assignment MIP formulations.

A new approach to version control

Abstract: A method for controlling versions of software and other hierarchically structured entities is presented. Using the variant structure principle, a particular version of an entire system is formed by combining the most relevant existing versions of the various components of the system. An algebraic version language that allows histories (numbered series), subversions (or variants), and joins is described. It is shown that the join operation is simply the lattice least upper bound and together with the variant structure principle, provides a systematic framework for recombining divergent variants. The utility of this approach is demonstrated using LEMUR, a programming environment for modular C programs, which was developed using itself. The ways in which this notion of versions is related to the possible world semantics of intensional logic are discussed. >