LEFT_IMP_EXISTS_CONV : conv
STRUCTURE
SYNOPSIS
Moves an existential quantification of the antecedent outwards through an implication.
DESCRIPTION
When applied to a term of the form (?x.P) ==> Q, the conversion LEFT_IMP_EXISTS_CONV returns the theorem:
   |- (?x.P) ==> Q = (!x'. P[x'/x] ==> Q)
where x' is a primed variant of x that does not appear free in the input term.
FAILURE
Fails if applied to a term not of the form (?x.P) ==> Q.
SEEALSO
HOL  Kananaskis-14