ON THE THEORY OF BOOLEAN FORMULAS:ALLOWABLE REPLACEMENTS FOR SUBFORMULAS

摘要

The theory of substitutions for Boolean formulas developed in a previous re¬port is applied here to the determination of those s -tuples of formulas that may be allowable replacements for s -tuples of subformulas of given Boolean formulas. The criteria of allowability are very general and flexible, yet may be expressed with great precision and ease. The results formalize and extend various known isolated instances. They may be used for the study of a large number of problems in the theory and application of Boolean formulas and functions.