Designing Efficient Controlled Languages for Ontologies Raffaella Bernardi, Diego Calvanese, and Camilo Thorne Abstract We describe a methodology to recognize efficient controlled natural lan- guages (CLs) that compositionally translate into ontology languages, and as such are suitable to be used in natural language front-ends to ontology-based systems. Efficiency in this setting is defined as the tractability (in the sense of computational complexity theory) of logical reasoning in such fragments, measured in the size of the data they aim to manage. In particular, to identify efficient CLs, we con- sider fragments corresponding to the DL-Lite familiy of description logics, known to underpin data intensive ontologies and systems. Our methodology exploits the link between syntax and semantics of natural language captured by categorial gram- mars, controlling the use of lexical terms that introduce logical structure outside the allowed fragments. A major role is played by the control of function words in- troducing logical operators in first-order formal semantics meaning representations. Finally, we conducted a preliminary analysis of semantically parsed English writ- ten corpora to show how empirical methods may be useful in identifying CLs that provide good trade-offs between coverage and efficiency. Key words: Controlled languages, description logics, DL-Lite, categorial gram- mars, semantic data complexity, data complexity. Camilo Thorne Free University of Bozen-Bolzano, Bolzano, Italy, e-mail: cthorne@inf.unibz.it Raffaella Bernardi University of Trento, Trento, Italy, e-mail: bernardi@disi.unitn.it Diego Calvanese Free University of Bozen-Bolzano, Bolzano, Italy, e-mail: calvanese@inf.unibz.it 1