Program algebra with a jump-shift instruction

Abstract: We study sequential programs that are instruction sequences with jump-shift instructions in the setting of PGA (ProGram Algebra). Jump-shift instructions preceding a jump instruction increase the position to jump to. The jump-shift instruction is not found in programming practice. Its merit is that the expressive power of PGA extended with the jump-shift instruction, is not reduced if the reach of jump instructions is bounded. This is used to show that there exists a finite-state execution mechanism that by making use of a counter can produce each finite-state thread from some program that is a finite or periodic infinite sequence of instructions from a finite set.