People v. Gilmour

Euclidean mathematics contains a number of general postulates — statements which are admitted to he true without the need for proof, such as is required to demonstrate the validity of a theorem.

*384Among such, postulates is one frequently referred to as the postulate of equality. It states: “ Things which are equal to the same thing or to equal things are equal to each other.”

Another postulate is the substitution postulate — “In any mathematical operation any thing may be substituted in the place of its equal.” (Geometry for the Practical Man, by J. E. Thompson, 3d ed. New York, 1962.)

These…