Theorem exbidh 1900

Description: Formula-building rule for existential quantifier (deduction form). (Contributed by NM, 26-May-1993.)

Hypotheses

Ref	Expression
exbidh.1	⊢ (𝜑 → ∀𝑥𝜑)
exbidh.2	⊢ (𝜑 → (𝜓 ↔ 𝜒))

Assertion

Ref	Expression
exbidh	⊢ (𝜑 → (∃𝑥𝜓 ↔ ∃𝑥𝜒))

Proof of Theorem exbidh

Step	Hyp	Ref	Expression
1		exbidh.1	. 2 ⊢ (𝜑 → ∀𝑥𝜑)
2		exbidh.2	. . 3 ⊢ (𝜑 → (𝜓 ↔ 𝜒))
3	2	alexbii 1866	. 2 ⊢ (∀𝑥𝜑 → (∃𝑥𝜓 ↔ ∃𝑥𝜒))
4	1, 3	syl 18	1 ⊢ (𝜑 → (∃𝑥𝜓 ↔ ∃𝑥𝜒))

This proof depends on syntax axioms:   → wi 4   ↔ wb 209  ∀wal 1568  ∃wex 1812

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1828  ax-4 1842

This proof depends on definitions:  df-bi 210  df-ex 1813

This theorem is used by:  exbidv  1954  exbid  2262  bj-elgab  37634  ac6s6  38881