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<h1>Mechanising the Metatheory of LF</h1>+ −
+ −
<h3>by Christian Urban, James Cheney and Stefan Berghofer</h3>+ −
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<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://nms.kcl.ac.uk/christian.urban/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://nms.kcl.ac.uk/christian.urban/Nominal/LF/LF.tgz">[LF.tgz]</A>+ −
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