Theorem 19.21bi

Description: Inference form of 19.21 and also deduction form of sp . (Contributed by NM, 26-May-1993)

	Ref	Expression
Hypothesis	19.21bi.1	$$⊢\phi \to \forall x\psi$$
Assertion	19.21bi	$$⊢\phi \to \psi$$

Proof

Step	Hyp	Ref	Expression
1		19.21bi.1	$$⊢\phi \to \forall x\psi$$
2		sp	$$⊢\forall x\psi \to \psi$$
3	1 2	syl	$$⊢\phi \to \psi$$