Formalising a derivation strategy for formal specifications from natural language requirements models

Natural language requirements models are useful during the first stages of software development. Formal methods help to increase software quality and reliability. In order to take advantage of both of them, we propose a requirements definition strategy which integrates them. We present in this paper the formalisation of a semiautomatic strategy to derive the types of a first initial specification in the RAISE specification language (RSL) from the Language Extended Lexicon (LEL), a natural language oriented model, which models the vocabulary of a domain. The strategy consists of a set of RSL-based derivation rules which provide a systematic and consistent way of transforming the information contained in the LEL into abstract and concrete RSL types.