Extended discourse representation structures in attempto controlled English

This technical report describes the extended discourse representation structures (DRS) derived from texts written in version 4 of Attempto Controlled English (ACE 4). The need to extend the standard DRS representation arose from the two requirements to adequately represent plural nouns introduced into ACE 4, and to perform logical deductions on ACE texts. An extended representation structure contains both the original ACE 4 text and its translation into a discourse representation structure – a closed logical formula using a syntactical variant of the language of first-order logic. 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. Furthermore, each logical atom gets an index relating it to the sentence of the ACE text from which it was derived