The equivalence relation that partitions switching functions into affine families leads to a natural graphic representation of the families. From the graphs, it is possible to derive information on the self-symmetries of switching functions and the relative symmetries of functions that are in the same family. A catalog of the structures of the 39 families of four-variable functions appears in the paper. The catalog and, more generally, the theory of affine equivalence are useful tools for the design of logic networks that contain exclusive-OR modules among the set of primitive building blocks.

This paper should cheer both system programmers and application programmers. The authors describe the methods used to measure the performance of both the GE-625/ 635 GECOS II operating system nd the user programs running under the operating system. Anyone who works on computer operating systems or who is involved in computer system measurement and improvement would probably find this paper interesting.

The hyperoctahedral group on the set of N-variable Boolean functions is defined. The problem of determining, given an arbitrary function, its equivalence class membership (type) is posed and, for the special case of four-variable functions, solved by a method that in use proved to be four times as rapid as computation of the conventional Golomb-Ninomiya[1],[2]invariants.