Formal semantics

The operational semantics in report chapter on “Formal semantics” replaces the denotational semantics in R5RS. The denotational semantics in R5RS has several problems, most seriously its incomplete treatment of the unspecific evaluation order of applications: the denotational semantics suggests that a single unspecified order is used. Modelling nondeterminism is generally difficult with denotational semantics, and an operational semantics allows specifying the unspecified evaluation order precisely.