---
title: "Efficient Parameterizable Type Expansion for Typed Feature Formalisms"
authors:
  - "Hans-Ulrich Krieger"
  - "Ulrich Schäfer"
doi: ""
url: "https://ijcai.org/proceedings/1995/184"
pdf: "https://ijcai.org/proceedings/1995/0184.pdf"
venue: "Proceedings of the Fourteenth International Joint Conference on Artificial Intelligence"
year: 1995
pages: "1428-1433"
track: "Natural Language"
keywords:
---

# Efficient Parameterizable Type Expansion for Typed Feature Formalisms

Hans-Ulrich Krieger, Ulrich Schäfer

*Proceedings of the Fourteenth International Joint Conference on Artificial Intelligence*, pages 1428-1433.

## Abstract

Over the l ast few years, constraint-based grammar formalisms have become the predominant paradigm in natural language processing and computational linguistics. From the viewpoint of computer science, typed feature structures can be seen as data structures that allow the representation of linguistic knowledge in a uniform fashion. Type expansion is an operation that makes constraints of a typed feature structure explicit and determines its satisfiability. We describe an efficient expansion algorithm that takes care of recursive type definitions and permits the exploration of different expansion strategies through the use of control knowledge. This knowledge is specified on a separate layer, independent of grammatical information. The algorithm, as presented in the paper, has been fully implemented in COMMON LISP and is an integrated part of the typed feature formalism TDC that is emp lo yed in several large NL projects.