Theorem bj-2exim

Description: Closed form of 2eximi . (Contributed by BJ, 6-May-2019)

	Ref	Expression
Assertion	bj-2exim	$$⊢\forall x\forall y\left(\phi \to \psi \right)\to \left(\exists x\exists y\phi \to \exists x\exists y\psi \right)$$

Proof

Step	Hyp	Ref	Expression
1		exim	$$⊢\forall y\left(\phi \to \psi \right)\to \left(\exists y\phi \to \exists y\psi \right)$$
2	1	aleximi	$$⊢\forall x\forall y\left(\phi \to \psi \right)\to \left(\exists x\exists y\phi \to \exists x\exists y\psi \right)$$