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2. Hdrug Applications

This chapter shortly lists a number of example applications which are part of the Hdrug distribution.

2.1. Ale

The Attribute-Logic Engine by Bob Carpenter and Gerald Penn is a freeware logic programming and grammar parsing and generation system. The following description is quote from the Ale Homepage

[Ale] integrates phrase structure parsing, semantic-head-driven
generation and constraint logic programming with typed feature
structures as terms. This generalizes both the feature structures of
PATR-II and the terms of Prolog II to allow type inheritance and
appropriateness specifications for features and values. Arbitrary
constraints may be attached to types, and types may be declared as
having extensional structural identity conditions. Grammars may also
interleave unification steps with logic program goal calls (as can
be done in DCGs), thus allowing parsing to be interleaved with other
system components. ALE was developed with an eye toward Head-Driven
Phrase Structure Grammar (HPSG), but it can also execute PATR-II
grammars, definite clause grammars (DCGs), Prolog, Prolog-II, and
LOGIN programs, etc. With suitable coding, it can also execute
several aspects of Lexical-Functional Grammar (LFG).

2.2. Alvey NL Tools

Definite-clause version of the grammar of the Alvey NL Tools, and a fragment of the lexicon. Thanks to John Carroll for making the grammar and test-set available. The accompanying README file states:

NOTICE: these files were supplied by John Carroll,, and are derived from a version of the ALVEY Natural Language Tools. Current information about these ALVEY NL Tools is available at

2.3. CFG

Tiny context-free grammar. Illustration what you need to do minimally to adapt a grammar / parser to Hdrug.

2.4. Constraint-based Categorial Grammar

Constraint-based Categorial Grammar for Dutch written by G.Bouma, slightly adopted by G. van Noord for Hdrug.

2.5. Definite Clause Grammar

Tiny DCG. Illustration what you need to do minimally to adapt a grammar / parser to Hdrug.

2.6. Chat-80

The classic Chat-80 system by Fernando Pereira and David Warren

2.7. Tree Adjoining Grammar

Small Tree Adjoining Grammar with nine (related) head-corner parsing algorithms for headed Lexicalized and Feature-based TAG's.

2.8. Semantic-head-driven Generation and Head-corner Parsing

DCG for Dutch, originally used as illustration for semantic-head-driven generation. Furthermore, some of the parsers were used for the timings of the paper co-authored with G. Bouma on the potential efficiency of head-driven parsing.

2.9. Extraposition Grammar

Extraposition grammars as described in Pereira's CL paper.

2.10. Delayed Evaluation of Lexical Rules

HPSG grammar for Dutch using delayed evaluation techniques to implement recursive lexical rules.

2.11. Stochastic Definite Clause Grammar

Experimental Stochastic Definite Clause Grammar by Robert Malouf.

2.12. Stochastic Head-driven Phrase Structure Grammar

Experimental Stochastic Head-driven Phrase Structure Grammar by Robert Malouf. This material was used by Rob's ESSLLI course (with Miles Osborne) in Helsinki 2001.

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