OR_EXISTS_CONVConv.OR_EXISTS_CONV : conv
Moves an existential quantification outwards through a disjunction.
When applied to a term of the form (?x.P) \/ (?x.Q), the
conversion OR_EXISTS_CONV returns the theorem:
|- (?x.P) \/ (?x.Q) = (?x. P \/ Q)
Fails if applied to a term not of the form
(?x.P) \/ (?x.Q).
Conv.EXISTS_OR_CONV, Conv.LEFT_OR_EXISTS_CONV,
Conv.RIGHT_OR_EXISTS_CONV