Journal of Logic, Language and Information

, Volume 18, Issue 3, pp 293–316

Associative Grammar Combination Operators for Tree-Based Grammars


DOI: 10.1007/s10849-009-9081-1

Cite this article as:
Sygal, Y. & Wintner, S. J of Log Lang and Inf (2009) 18: 293. doi:10.1007/s10849-009-9081-1


Polarized unification grammar (PUG) is a linguistic formalism which uses polarities to better control the way grammar fragments interact. The grammar combination operation of PUG was conjectured to be associative. We show that PUG grammar combination is not associative, and even attaching polarities to objects does not make it order-independent. Moreover, we prove that no non-trivial polarity system exists for which grammar combination is associative. We then redefine the grammar combination operator, moving to the powerset domain, in a way that guarantees associativity. The method we propose is general and is applicable to a variety of tree-based grammar formalisms.


Polarized unification grammar Grammatical formalisms Modularity Grammar combination 

Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  1. 1.Department of Computer ScienceUniversity of HaifaHaifaIsrael

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