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Hdrug. A Flexible and Extendible Development Environment for Natural Language Processing.

Gertjan van Noord
Gosse Bouma

Alfa-informatica & BCN,
University of Groningen


Hdrug is an environment to develop grammars, parsers and generators for natural languages. The package is written in Sicstus Prolog and Tcl/Tk. The system provides a graphical user interface with a command interpreter, and a number of visualisation tools, including visualisation of feature structures, syntax trees, type hierarchies, lexical hierarchies, feature structure trees, definite clause definitions, grammar rules, lexical entries, and graphs of statistical information of various kinds.

Hdrug is designed to be as flexible and extendible as possible. This is illustrated by the fact that Hdrug has been used both for the development of practical real-time systems, but also as a tool to experiment with new theoretical notions and alternative processing strategies. Grammatical formalisms that have been used range from context-free grammars to concatenative feature-based grammars (such as the grammars written for ALE) and non-concatenative grammars such as Tree Adjoining Grammars.

Noord G.J.M. van