MK_EXISTS : (thm -> thm)
STRUCTURE
Drule
SYNOPSIS
Existentially quantifies both sides of a universally quantified equational theorem.
DESCRIPTION
When applied to a theorem A |- !x. t1 = t2, the inference rule MK_EXISTS returns the theorem A |- (?x. t1) = (?x. t2). 
       A |- !x. t1 = t2
   --------------------------  MK_EXISTS
    A |- (?x. t1) = (?x. t2)

FAILURE
Fails unless the theorem is a singly universally quantified equation.
SEEALSO
AP_TERM, EXISTS_EQ, GEN, LIST_MK_EXISTS, MK_ABS
HOL  Kananaskis-14