Language is one of our most fundamental cognitive skills. This Special Research Area is developing a new approach to modeling the linguistic system. The starting point is the hypothesis that although the cognitive core of language ability is based on logical-symbolic calculations, it is embedded in a cognitive system of a stochastic nature. As an interface between the symbolic and stochastic components, grammar makes use of the central optimization factors of redundancy and deficiency, which can be behind linguistic operations and which enable the processing of both under-specified and over-specified input. The Special Research Area bundles the extraordinarily strong linguistic research at the Universities of Graz, Vienna and Salzburg and deals with uniformly defined, comprehensive empirical areas of grammar (pronouns and ellipses). Sub-projects will examine, classify, and model these areas both theoretically and empirically from the perspective of the concepts of redundancy and deficiency. The expected findings  promise not only a better understanding of the fundamental mechanisms of the grammatical system, but also open up new perspectives for key questions in cognitive science regarding the role of language in cognition.