 
Summary: Coercive Subtyping in Lambdafree Logical Frameworks
Robin Adams
Royal Holloway, University of London
robin@cs.rhul.ac.uk
Abstract
We show how coercive subtyping may be added to a lambdafree
logical framework, by constructing the logical framework TF<, an
extension of the lambdafree logical framework TF with coercive
subtyping. Instead of coercive application, TF< makes use of a
typecasting operation. We develop the metatheory of the resulting
framework, including providing some general conditions under
which typecasting in an object theory with coercive subtyping is
decidable. We show how TF< may be embedded in the logical
framework LF, and hence how results about LF may be deduced
from results about TF<.
Categories and Subject Descriptors F.4.1 [Mathematical Logic
and Formal Languages]: Mathematical LogicLambda calculus
and related systems, Mechanical theorem proving; I.2.3 [Artifi
cial Intelligence]: Deduction and Theorem ProvingMetatheory;
I.2.4 [Artificial Intelligence]: Knowledge Representation
