Theorem mobid 2628

Description: Formula-building rule for the at-most-one quantifier (deduction form). (Contributed by NM, 8-Mar-1995.) Remove dependency on ax-10 2139, ax-11 2154, ax-13 2384. (Revised by BJ, 14-Oct-2022.) (Proof shortened by Wolf Lammen, 18-Feb-2023.)

Hypotheses

Ref	Expression
mobid.1	⊢ Ⅎ𝑥𝜑
mobid.2	⊢ (𝜑 → (𝜓 ↔ 𝜒))

Assertion

Ref	Expression
mobid	⊢ (𝜑 → (∃*𝑥𝜓 ↔ ∃*𝑥𝜒))

Proof of Theorem mobid

Step	Hyp	Ref	Expression
1		mobid.1	. . 3 ⊢ Ⅎ𝑥𝜑
2		mobid.2	. . 3 ⊢ (𝜑 → (𝜓 ↔ 𝜒))
3	1, 2	alrimi 2206	. 2 ⊢ (𝜑 → ∀𝑥(𝜓 ↔ 𝜒))
4		mobi 2624	. 2 ⊢ (∀𝑥(𝜓 ↔ 𝜒) → (∃*𝑥𝜓 ↔ ∃*𝑥𝜒))
5	3, 4	syl 17	1 ⊢ (𝜑 → (∃*𝑥𝜓 ↔ ∃*𝑥𝜒))

Syntax hints:   → wi 4   ↔ wb 208  ∀wal 1529  Ⅎwnf 1778  ∃*wmo 2614

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1790  ax-4 1804  ax-5 1905  ax-6 1964  ax-7 2009  ax-12 2170

This theorem depends on definitions:  df-bi 209  df-an 399  df-ex 1775  df-nf 1779  df-mo 2616

This theorem is referenced by:  moanim  2699  rmobida  3391  rmoeq1f  3399  funcnvmpt  30404