A Review of: “PROBLEM - SOLVING METHODS IN ARTIFICIAL INTELLIGENCE”, by Nils J. Nilsson. McGraw-Hill,New York, 1971. 255 pp.

After defining systems that can be represented by scators it is shown that the merging of such systems is conveniently modelled by scator addition. It is shown that scator addition although not generally associative will be so if a certain function involved is solution of a functional equation whose general solution is found. Finally after defining scator derivatives it is shown that systems with continuous merging lead to differential equations in scators.