RenTAL (Grammar converter for LTAG)

RenTAL is a system that converts (feature-based) LTAG grammars into HPSG-style grammars. The system is developed and maintained mainly by Naoki Yoshinaga, a member of Tsujii Lab.



The RenTAL system converts LTAG lexicon (a set of elementary trees) into HPSG lexicon (a set of feature structures) by encoding a tree structure in a stack. A set of pre-determined rule manipulates the stack to emulate substitution and adjunction.

RenTAL overview

Although the converter does not analyze feature percolation provided in the original LTAG grammars, it defines a formal link between the processing architecture that underlies LTAG and the processing architecture that underlies HPSG that is defined by the typed feature structure and a set of language-independent principles (e.g., Immediate Dominance Principle, Head Feature Princpile, and Subcategorization Principle).

This conversion guarantees strong equivalence where the obtained HPSG grammar generates parse results equivalent to those of the original LTAG grammar. This system thus allows HPSG-based applications to make use of existing LTAG grammars without losing LTAG syntactic analysis. It also enables a precise comparison between the two formalisms from both computational and linguistic viewpoints.


The latest version of RenTAL (including the XTAG English Grammar of Release 2.24.2001, convertible by RenTAL) is available at here (version 5.22.2003). Following the procedure in the tujiilab software package page, you can obtain a large-scale HPSG-system compatible grammar.

NOTE: RenTAL system is implemented in the programming language LiLFeS. See also the LiLFeS home page. The current version of RenTAL is implemented with (old) lilfes, version up to 1.096. We are now conducting to update the RenTAL for the newer liblilfes.

Selected Publications

[1] YOSHINAGA Naoki, MIYAO Yusuke, TORISAWA Kentaro, and TSUJII Jun'ichi. 2003. Parsing comparison across grammar formalisms using strongly equivalent grammars. Journal of Traitement Automatique des Langues, a special issue on Evolutions in Parsing. vol. 44, num. 3.
[2] YOSHINAGA Naoki and MIYAO Yusuke. 2002. Grammar Conversion from LTAG to HPSG. In the European Student Journal on Language and Speech, a special issue on the language sections of the 6th ESSLLI student session. 2001. (the original paper presented in the student session).

All questions and suggestions are welcome. Please send e-mail to YOSHINAGA Naoki (yoshinag at
$ Last modified at Thu Jan 31 11:11:10 2013 $