{78 () the Vlisp Veriied Scheme System *

The vlisp project has produced a rigorously veriied compiler from Scheme to byte codes, and a veriied interpreter for the resulting byte codes. The oocial denotational semantics for Scheme provides the main criterion of correctness. The Wand-Clinger technique was used to prove correctness of the primary compiler step. Then a state machine operational semantics is proved to be faithful to the denotational semantics. The remainder of the implementation is veriied by a succession of state machine reenement proofs. These include proofs that garbage collection is a sound implementation strategy, and that a particular garbage collection algorithm is correct.