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TDL - A Type Description Language for HPSG. Part 1: Overview

Hans-Ulrich Krieger; Ulrich Schäfer
DFKI, DFKI Research Reports (RR), Vol. 94-37, 1994.


This paper presents TDL, a typed feature-based language and inference system, which is specifically designed to support highly lexicalized grammar theories like HPSG. TDL allows the user to define (possibly recursive) hierarchically-ordered types, consisting of type constraints and feature constraints over the standard boolean connectives. TDL distinguishes between avm types (open-world reasoning), sort types (closed-world reasoning), built-in types and atoms, and allows the declaration of partitions and incompatible types. Working with partially as well as with fully expanded types is possible, both at definition time and at run time. TDL is incremental, i.e., it allows the redefinition of types and the use of undefined types. Efficient reasoning is accomplished through four specialized reasoners: i. syntactic simplifier, ii. type hierarchy reasoning, iii. memoization, and iv. type expansion.

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