Hdrug is an environment to develop logic grammars / parsers / generators for natural languages. The package is written in Sicstus Prolog version 3 and uses the tcltk library for its graphical user interface.
Hdrug offers various tools to visualize lexical entries, grammar rules, definite-clause definitions, parse trees, feature structures, lexical- rule- and type-hierarchies, graphs of the comparison of different parsers on a corpus of test sentences etc., in a Tk widget, LaTeX/DVI format, and the Clig system.
The package comes with a number of example grammars, including a Categorial Grammar, a Tree Adjoining Grammar, a Unification Grammar in the spirit of Head-driven Phrase Structure Grammar, an Extraposition Grammar and a Definite Clause Grammar. Each of the grammars comes with a set of parsers, such as Earley-like chart parsers, left-corner parsers and head-driven parsers. Some grammars come with variants of the head-driven generator.
The distribution also contains an interface to the ALE system.
Hdrug allows for easy comparison of different parsers/generators; it has extensive possibilities to compile feature equations into Prolog terms; it can produce graphical (Tk), and ordinary Prolog output of trees, feature structures, Prolog terms (and combinations thereof), plotted graphs of statistical information, and tables of statistical information. Using just menu's and buttons, a command interpreter, or a Prolog prompt, it is possible to parse sentences, generate sentences from logical form representations, view the parse trees that are derived by the parser or generator, change a particular version of the parser on the fly, compare the results of parsing the same sentence(s) with a set of different parsers, etc.
DOWNLOAD SOFTWARE You have a choice from one of the following packages (copyright):
NEW The Windows version has finally been updated again (september 2006).
The Reference Manual . The documentation is also included in the distribution, and available through the graphical user interface.
An Example Session.
Gertjan van Noord, Gosse Bouma. HDRUG. A Flexible and Extendible Development Environment for Natural Language Processing. Proceedings of the EACL/ACL Workshop ENVGRAM, Computational Environments for Grammar Development and Linguistic Engineering. [ postscript, html ]