Typed feature structures are used extensively for the specification of linguistic information in many formalisms. The subsumption relation orders TFSs by their information content. We prove that subsumption of acyclic TFSs is well founded, whereas in the presence of cycles general TFS subsumption is not well founded. We show an application of this result for parsing, where the well-foundedness of subsumption is used to guarantee termination for grammars that are off-line parsable. We define a new version of off-line parsability that is less strict than the existing one; thus termination is guaranteed for parsing with a larger set of grammars.
Bibliographical noteFunding Information:
This work is supported by a grant from the Israeli Ministry of Science: “Programming Languages Induced Computational Linguistics.” The work of the second author was also partially supported by the Fund for the Promotion of Research in the Technion. We wish to thank the anonymous referees for their enlightening comments.
- Computational linguistics
- Feature structures
ASJC Scopus subject areas
- Computer Science (miscellaneous)
- Linguistics and Language