Abstract   The computational model of Blum, Shub, and Smale (1989,  Bull. Amer. Math. Soc.  21,  1-46) yields a numerous number of different algorithm-classes if the allowed set of instructions is varied. For two such classes we consider the " P  =  NP ?" problem as well as the question of whether the  NP - problems are decidable.
['Klaus Meer']
Real Number Models under Various Sets of Operations