Optimizing Higher-Order Pattern Unification

@inproceedings{Pientka2003OptimizingHP,
  title={Optimizing Higher-Order Pattern Unification},
  author={Brigitte Pientka and Frank Pfenning},
  booktitle={CADE},
  year={2003}
}
We present an abstract view of existential variables in a dependently typed lambda-calculus based on modal type theory. This allows us to justify optimizations to pattern unification such as linearization, which eliminates many unnecessary occurs-checks. The presented modal framework explains a number of features of the current implementation of higher-order unification in Twelf and provides insight into several optimizations. Experimental results demonstrate significant performance improvement… 
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