# Banishing the rule of substitution for functional variables

@article{Henkin1953BanishingTR, title={Banishing the rule of substitution for functional variables}, author={Leon Henkin}, journal={Journal of Symbolic Logic}, year={1953}, volume={18}, pages={201 - 208} }

Let and be (well-formed) formulas of the functional calculus, let c be an n-adic functional variable, and let a1, …, an be distinct individual variables. Church has defined the metalogical notation to indicate the formula resulting from when each part of of the form c{1, …, n) (such that the occurrence of c is free in ) is replaced by the formula which arises from by replacing every free occurrence of ai by i, i, = 1, …, n. (Here 1, …, n may be any individual variables or constants, not…

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