Abstract The semantics of hardware description languages can be represented in higher order logic. This provides a formal definition that is suitable for machine processing. Experiments are in progress at Cambridge to see whether this method can be the basis of practical tools based on the HOL theorem-proving assistant. Three languages are being investigated: ELLA, Silage and VHDL. The approaches taken for these languages are compared and current progress on building semantically-based theorem-proving tools is discussed.

This paper describes a translation of the complex calculus of dependent type theory into the relatively simpler higher order logic originally introduced by Church. In particular, it shows how type dependency as found in Martin-Löf's Intuitionistic Type Theory can be simulated in the formulation of higher order logic mechanized by the HOL theorem-proving system. The outcome is a theorem prover for dependent type theory, built on top of HOL, that allows natural and flexible use of set-theoretic notions. A bit more technically, the language of the resulting theorem-prover is the internal language of a (boolean) topos (as formulated by Phoa).