EXISTS_EQ : (term -> thm -> thm)

- STRUCTURE
- SYNOPSIS
- Existentially quantifies both sides of an equational theorem.
- DESCRIPTION
- When applied to a variable x and a theorem whose conclusion is equational, A |- t1 = t2, the inference rule EXISTS_EQ returns the theorem A |- (?x. t1) = (?x. t2), provided the variable x is not free in any of the assumptions.
A |- t1 = t2 ------------------------ EXISTS_EQ "x" [where x is not free in A] A |- (?x.t1) = (?x.t2)

- FAILURE
- Fails unless the theorem is equational with both sides having type bool, or if the term is not a variable, or if the variable to be quantified over is free in any of the assumptions.
- SEEALSO

HOL Kananaskis-14