Semantics-to-Syntax Analyses of Algorithms

Abstract

Alan Turing pioneered semantics-to-syntax analysis of algorithms. It is a kind of analysis where you start with a large semantically defined species of algorithms, and you finish up with a syntactic artifact, typically a computation model, that characterizes the species. The task of analyzing a large species of algorithms seems daunting if not impossible. As in quicksand, one needs a rescue point, a fulcrum. In computation analysis, a fulcrum is a particular viewpoint on computation that clarifies and simplifies things to the point that analysis become possible. We review from that point of view Turing’s analysis of human-executable computation, Kolmogorov’s analysis of sequential bit-level computation, Gandy’s analysis of a species of machine computation, and our own analysis of sequential computation.