Discourse Representation Structures for ACE 6.5

This technical report describes the discourse representation structures (DRS) derived from texts written in version 6.5 of Attempto Controlled English (ACE 6.5). The description is done by an exhaustive set of examples. Among other things, ACE 6.5 supports modal statements, negation as failure, and sentence subordination. These features require an extended form of discourse representation structures. The discourse representation structure itself uses a reified, or ‘flat ’ notation, meaning that its atomic conditions are built from a small number of predefined predicates that take constants standing for words of the ACE text as their arguments