Theorem bnj101

Description: First-order logic and set theory. (Contributed by Jonathan Ben-Naim, 3-Jun-2011) (New usage is discouraged.)

	Ref	Expression
Hypotheses	bnj101.1	⊢ ∃ 𝑥 𝜑
	bnj101.2	⊢ ( 𝜑 → 𝜓 )
Assertion	bnj101	⊢ ∃ 𝑥 𝜓

Proof

Step	Hyp	Ref	Expression
1		bnj101.1	⊢ ∃ 𝑥 𝜑
2		bnj101.2	⊢ ( 𝜑 → 𝜓 )
3	1 2	eximii	⊢ ∃ 𝑥 𝜓