Project description A controlled natural language is a fragment of natural language with precisely defined syntax and semantics. Controlled natural languages are intended for use in situations where various language processing tasks—for example, translation or query answering—need to be performed efficiently and reliably, either by computers or by humans. One attractive feature of controlled natural languages is that a range of techniques developed in theoretical and computational linguistics can be applied relatively unproblematically, thus mapping the¬†controlled natural language in question into a logical formalism suitable for machine reasoning. The aim of this project is to use these techniques to develop and implement controlled natural languages whose complexity-theoretic properties can be precisely analysed.