The VLISP project showed how to produce a comprehensively verified implemen tation for a programming language, namely Scheme 4, 15). Some of the major elements in this verification were: The proof was based on the Clinger-Rees denotational semantics of Scheme given in 15). Our goal was to produce a "warts-and-all" verification of a real language. With very few exceptions, we constrained ourselves to use the se mantic specification as published. The verification was intended to be rigorous, but. not. complet.ely formal, much in the style of ordinary mathematical discourse. Our goal was to...