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<h1>Mechanising the Metatheory of LF</h1>
<h3>by Christian Urban, James Cheney and Stefan Berghofer</h3>
<h4>Abstract</h4>
LF is a dependent type theory in which many other formal systems can
be conveniently embedded. However, correct use of LF relies on
nontrivial metatheoretic developments such as proofs of correctness
of decision procedures for LF's judgments. Although detailed
informal proofs of these properties have been published, they have
not been formally verified in a theorem prover. We have formalized
these properties within Isabelle/HOL using
the Nominal Datatype Package, closely following a recent article by
Harper and Pfenning. In the process, we identified and resolved a
gap in one of the proofs and a small number of minor lacunae
in others. We also formally derive a version of the type checking
algorithm from which Isabelle/HOL can generate executable code.
Besides its intrinsic interest, our formalization
provides a foundation for studying the adequacy of LF encodings, the
correctness of Twelf-style metatheoretic reasoning, and the
metatheory of extensions to LF.<P>
<b>Technical Report</b>
<A HREF="http://isabelle.in.tum.de/nominal/LF/techreport.pdf">[pdf]</A><BR>
(This technical report contains in some sections more details of our development
than we presented in the LICS'08 paper, and also a new section on the
locally nameless representation of binders and on code generation.)
<p>
<b>Nominal Isabelle Development</b>
<p> (includes all three developments discussed in the technical report)
<A HREF="http://isabelle.in.tum.de/nominal/LF/LF.tgz">[LF.tgz]</A>
<p>
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Last modified: Fri Oct 23 17:42:50 CEST 2009
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