Theorem 19.23bi

Description: Inference form of Theorem 19.23 of Margaris p. 90, see 19.23 . (Contributed by NM, 12-Mar-1993)

	Ref	Expression
Hypothesis	19.23bi.1	⊢ ( ∃ 𝑥 𝜑 → 𝜓 )
Assertion	19.23bi	⊢ ( 𝜑 → 𝜓 )

Proof

Step	Hyp	Ref	Expression
1		19.23bi.1	⊢ ( ∃ 𝑥 𝜑 → 𝜓 )
2		19.8a	⊢ ( 𝜑 → ∃ 𝑥 𝜑 )
3	2 1	syl	⊢ ( 𝜑 → 𝜓 )