A context-free superset approximation of unification-based grammars

We present a simple and intuitive approximation method for turning unification-based grammars into context-free grammars. We apply our method to several grammars and report on the quality of the approximation. We also present several methods that speed up the approximation process and that might be interesting to other areas of unification-based processing. Finally, we introduce a novel disambiguation method for unification grammars which is based on probabilistic context-free approximations.

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