Post Conference Tutorial




XLE and XFR: A Grammar Development Platform with a Parser/Generator and Rewrite System


Miriam Butt

Universitaet Konstanz, Germany


Tracy Holloway King

Palo Alto Research Center





This tutorial provides an introduction to writing large-scale, robust grammars with XLE, a grammar development platform designed by PARC (Palo Alto Research Center).  It will further introduce the use of the ordered rewrite system XFR to manipulate the grammar output for NLP application.  XLE includes a parser/generator with special tools built in to aid grammar development, as well as a general purpose rewrite system geared to the manipulation of XLE parser output.  The grammars use the Lexical-Functional Grammar (LFG) formalism.


The tutorial will be organized as follows.  First, we discuss the process of building a grammar: the formulation of rules, the integration of lexicons and finite-state morphological analyzers, and the use of templates to capture generalizations.  We then discuss the use of several robustness techniques: FSM guessers, the fragment grammar, and optimality theory (OT) marks.  During the second half of the tutorial, we discuss reversing the grammar for generation, the integration of stochastic methods for disambiguation and the use of the rewrite system for transfer and knowledge representation.  Finally, we briefly outline how such grammars can be used in applications like machine translation, sentence condensation, question-answer systems and computer assisted language learning.