P′′

P double prime is a minimalist programming language created by the mathematician Corrado Bohm in 1964 to describe a family of Turing machines. Its instruction set, built around a small number of primitive operations for incrementing and comparing values and structuring control flow, gave one of the earliest formal demonstrations of the single-entry, single-exit principle that later became central to structured programming. Bohm's work on P double prime predates and influenced Edsger Dijkstra's later advocacy for structured programming, and the language remains cited in computer science as an early example of a Turing-complete language reduced to a handful of primitive constructs.