15-851
Computation & Deduction
Spring 1997
Frank Pfenning

Lecture 9: Representing Type Preservation

We deepen our analysis of parametric and hypothetical judgments by studying the proof of type preservation in the context of a representation in LF. It turns out that the framework already has the necessary feature to give an elegant representation of type preservation. The punch line is an encoding of the substitution lemma for typing derivations by meta-level beta-reduction.
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