629 ;;Quote: defines D and D' control structures: basic actions, composition, conditionals, repetitions

632 ;;Quote: program structures are path-wise convertible if they define the same sequence of primitive actions and predicates for every input

632 ;;Quote: program structures are semantically convertible if both compute the same function from the same set of primitive actions and predicates

632 ;;Quote: Bohm and Jacopini's paper proved that L-programs were functionally equivalent to D-structured programs with extra control variables on a stack

634 ;;Quote: Kosaraju defined a hierarchy of control structures under semantic conversions; D and D' at bottom, L (goto) at top

634+ ;;Quote: in Kosaraju's control structure hierarchy, 'exit' statements added power to D and D' structures

637 ;;Quote: the need for high level control structures such as 'exit' statements is not proven

637 ;;Quote: internal 'exit' statements in a control structure can be hidden in the code yet are very important

638 ;;Quote: D'-structures preserve the one-in, one-out property of D-structures while adding a lot of notational convenience; recommended