《005.A Tree Transducer Model for Synchronous Tree-Adjoining Grammars》.pdf

A Tree Transducer Model for Synchronous Tree-Adjoining Grammars Andreas Maletti Universitat Rovira i Virgili Avinguda de Catalunya 25, 43002 Tarragona, Spain. andreas.maletti@urv.cat Abstract tion phenomena. Instead Shieber (2007) suggests a yet more powerful mechanism, synchronous A characterization of the expressive power tree-adjoining grammars (STAGs) as introduced of synchronous tree-adjoining grammars (STAGs) in terms of tree transducers (or by Shieber and Schabes (1990), that can capture certain (mildly) context-sensitive features of natu- equivalently, synchronous tree substitution ral language. In the tradition of Shieber (2004), a grammars) is developed. Essentially, a characterization of the power of STAGs in terms STAG corresponds to an extended tree of bimorphims was developed by Shieber (2006). transducer that uses explicit substitution in The bimorphisms used are rather unconventional both the input and output. This characteri- because they consist of a regular tree language and zation allows the easy integration of STAG into toolkits for extended tree transducers. two embedded tree transducers (inste