Left Corner Parser for Tree Insertion Grammars

Tree Adjoining Grammar (TAG) is a grammar formalism that has become very popular for the description of natural languages, however, this context-sensitive formalism entails important computation costs (O(n6)-time). Tree Insertion Grammar (TIG) is a compromise between Context Free Grammar (CFG) and TAG that can be parsed in O(n3) - time. In the literature, just two Earley-like parsers for TIGs have been defined. In this paper, we define a new variant of Earley-like parser for TIGs. In order to improve the performance of this parser, we show how the left corner relation for CFG can be generalized to the case of TIG and we present an efficient parser for TIG that uses this relation.