Theorem ch2var 16966

Description: Implicit substitution of 𝑦 for 𝑥 and 𝑡 for 𝑧 into a theorem. (Contributed by BJ, 17-Oct-2019.)

Hypotheses

Ref	Expression
ch2var.nfx	⊢ Ⅎ𝑥𝜓
ch2var.nfz	⊢ Ⅎ𝑧𝜓
ch2var.maj	⊢ ((𝑥 = 𝑦 ∧ 𝑧 = 𝑡) → (𝜑 ↔ 𝜓))
ch2var.min	⊢ 𝜑

Assertion

Ref	Expression
ch2var	⊢ 𝜓

Distinct variable groups:   𝑥,𝑧   𝑥,𝑡

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

Proof of Theorem ch2var

Step	Hyp	Ref	Expression
1		ch2var.nfx	. . 3 ⊢ Ⅎ𝑥𝜓
2		ch2var.nfz	. . 3 ⊢ Ⅎ𝑧𝜓
3		ch2var.maj	. . . 4 ⊢ ((𝑥 = 𝑦 ∧ 𝑧 = 𝑡) → (𝜑 ↔ 𝜓))
4	3	biimpd 144	. . 3 ⊢ ((𝑥 = 𝑦 ∧ 𝑧 = 𝑡) → (𝜑 → 𝜓))
5	1, 2, 4	2spim 16965	. 2 ⊢ (∀𝑧∀𝑥𝜑 → 𝜓)
6		ch2var.min	. . 3 ⊢ 𝜑
7	6	ax-gen 1502	. 2 ⊢ ∀𝑥𝜑
8	5, 7	mpg 1504	1 ⊢ 𝜓

This proof depends on syntax axioms:   → wi 4   ∧ wa 104   ↔ wb 105  ∀wal 1400  Ⅎwnf 1513

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-5 1500  ax-gen 1502  ax-ie1 1546  ax-ie2 1547  ax-4 1563  ax-17 1579  ax-i9 1583  ax-ial 1587

This proof depends on definitions:  df-bi 117  df-nf 1514

This theorem is used by:  ch2varv  16967