Theorem chvarfv 1700

Description: Implicit substitution of 𝑦 for 𝑥 into a theorem. Version of chvar 1757 with a disjoint variable condition. (Contributed by Raph Levien, 9-Jul-2003.) (Revised by BJ, 31-May-2019.)

Hypotheses

Ref	Expression
chvarfv.nf	⊢ Ⅎ𝑥𝜓
chvarfv.1	⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓))
chvarfv.2	⊢ 𝜑

Assertion

Ref	Expression
chvarfv	⊢ 𝜓

Distinct variable group:   𝑥,𝑦

Allowed substitution hints:   𝜑(𝑥,𝑦)   𝜓(𝑥,𝑦)

Proof of Theorem chvarfv

Step	Hyp	Ref	Expression
1		chvarfv.nf	. . 3 ⊢ Ⅎ𝑥𝜓
2		chvarfv.1	. . . 4 ⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓))
3	2	biimpd 144	. . 3 ⊢ (𝑥 = 𝑦 → (𝜑 → 𝜓))
4	1, 3	spimfv 1699	. 2 ⊢ (∀𝑥𝜑 → 𝜓)
5		chvarfv.2	. 2 ⊢ 𝜑
6	4, 5	mpg 1451	1 ⊢ 𝜓

Syntax hints:   → wi 4   ↔ wb 105  Ⅎwnf 1460

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-5 1447  ax-gen 1449  ax-ie1 1493  ax-ie2 1494  ax-4 1510  ax-i9 1530  ax-ial 1534

This theorem depends on definitions:  df-bi 117  df-nf 1461

This theorem is referenced by:  fproddivapf  11641  fprodsplitf  11642