This paper argues that individual architectural styles are ways to express different theories of architecture. These theories, in turn, are related to the architectis design purposes or goals. In order to understand the cognitive process involved in the creation of a particular language or style goals have to be decomposed in subgoals, which will be related, step-by-step, to the vocabulary and syntactic rules adopted by these architects. The study should contribute to the development of models allowing the incorporation of cognitive processes in the generation of synthetic grammars. It is assumed that this will be made possible through the correlation between semantic rules and syntactic rules in shape grammars. As a case, this paper analyses semantic extensions of the architectural language of the Brazilian architect Oscar Niemeyer defined by the constructive approach.