Polynomially parsable unification grammars

Hadas Peled, Shuly Wintner

Research output: Contribution to journalArticlepeer-review


Unification grammars (UGs) are a grammatical formalism that underlies several contemporary linguistic theories, including lexical-functional grammar and head-driven phrase-structure grammar. UG is an especially attractive formalism because of its expressivity, which facilitates the expression of complex linguistic structures and relations. Formally, UG is Turing-complete, generating the entire class of recursively enumerable languages. This expressivity, however, comes at a price: the universal recognition problem is undecidable for arbitrary unification grammars. We define a constrained version of UG that is equivalent to range concatenation grammar, a formalism that generates exactly the class of languages recognizable in deterministic polynomial time. We thus obtain a constrained unification grammar formalism that guarantees efficient processing.

Original languageEnglish
Pages (from-to)1167-1202
Number of pages36
JournalJournal of Logic and Computation
Issue number5
StatePublished - 30 Sep 2010

Bibliographical note

Publisher Copyright:
© 2013 The Author. Published by Oxford University Press. All rights reserved.


  • Unification grammars
  • parsing
  • range concatenation grammar
  • universal recognition problem

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Software
  • Arts and Humanities (miscellaneous)
  • Hardware and Architecture
  • Logic


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