Theorem sbcom2v 1978

Description: Lemma for proving sbcom2 1980. It is the same as sbcom2 1980 but with additional distinct variable constraints on 𝑥 and 𝑦, and on 𝑤 and 𝑧. (Contributed by Jim Kingdon, 19-Feb-2018.)

Assertion

Ref	Expression
sbcom2v	⊢ ([𝑤 / 𝑧][𝑦 / 𝑥]𝜑 ↔ [𝑦 / 𝑥][𝑤 / 𝑧]𝜑)

Distinct variable groups:   𝑥,𝑤,𝑧   𝑥,𝑦,𝑧

Allowed substitution hints:   𝜑(𝑥,𝑦,𝑧,𝑤)

Proof of Theorem sbcom2v

Step	Hyp	Ref	Expression
1		alcom 1471	. . 3 ⊢ (∀𝑧∀𝑥(𝑥 = 𝑦 → (𝑧 = 𝑤 → 𝜑)) ↔ ∀𝑥∀𝑧(𝑥 = 𝑦 → (𝑧 = 𝑤 → 𝜑)))
2		bi2.04 247	. . . . . 6 ⊢ ((𝑥 = 𝑦 → (𝑧 = 𝑤 → 𝜑)) ↔ (𝑧 = 𝑤 → (𝑥 = 𝑦 → 𝜑)))
3	2	albii 1463	. . . . 5 ⊢ (∀𝑥(𝑥 = 𝑦 → (𝑧 = 𝑤 → 𝜑)) ↔ ∀𝑥(𝑧 = 𝑤 → (𝑥 = 𝑦 → 𝜑)))
4		19.21v 1866	. . . . 5 ⊢ (∀𝑥(𝑧 = 𝑤 → (𝑥 = 𝑦 → 𝜑)) ↔ (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝜑)))
5	3, 4	bitri 183	. . . 4 ⊢ (∀𝑥(𝑥 = 𝑦 → (𝑧 = 𝑤 → 𝜑)) ↔ (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝜑)))
6	5	albii 1463	. . 3 ⊢ (∀𝑧∀𝑥(𝑥 = 𝑦 → (𝑧 = 𝑤 → 𝜑)) ↔ ∀𝑧(𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝜑)))
7		19.21v 1866	. . . 4 ⊢ (∀𝑧(𝑥 = 𝑦 → (𝑧 = 𝑤 → 𝜑)) ↔ (𝑥 = 𝑦 → ∀𝑧(𝑧 = 𝑤 → 𝜑)))
8	7	albii 1463	. . 3 ⊢ (∀𝑥∀𝑧(𝑥 = 𝑦 → (𝑧 = 𝑤 → 𝜑)) ↔ ∀𝑥(𝑥 = 𝑦 → ∀𝑧(𝑧 = 𝑤 → 𝜑)))
9	1, 6, 8	3bitr3i 209	. 2 ⊢ (∀𝑧(𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝜑)) ↔ ∀𝑥(𝑥 = 𝑦 → ∀𝑧(𝑧 = 𝑤 → 𝜑)))
10		sb6 1879	. . 3 ⊢ ([𝑤 / 𝑧][𝑦 / 𝑥]𝜑 ↔ ∀𝑧(𝑧 = 𝑤 → [𝑦 / 𝑥]𝜑))
11		sb6 1879	. . . . 5 ⊢ ([𝑦 / 𝑥]𝜑 ↔ ∀𝑥(𝑥 = 𝑦 → 𝜑))
12	11	imbi2i 225	. . . 4 ⊢ ((𝑧 = 𝑤 → [𝑦 / 𝑥]𝜑) ↔ (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝜑)))
13	12	albii 1463	. . 3 ⊢ (∀𝑧(𝑧 = 𝑤 → [𝑦 / 𝑥]𝜑) ↔ ∀𝑧(𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝜑)))
14	10, 13	bitri 183	. 2 ⊢ ([𝑤 / 𝑧][𝑦 / 𝑥]𝜑 ↔ ∀𝑧(𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝜑)))
15		sb6 1879	. . 3 ⊢ ([𝑦 / 𝑥][𝑤 / 𝑧]𝜑 ↔ ∀𝑥(𝑥 = 𝑦 → [𝑤 / 𝑧]𝜑))
16		sb6 1879	. . . . 5 ⊢ ([𝑤 / 𝑧]𝜑 ↔ ∀𝑧(𝑧 = 𝑤 → 𝜑))
17	16	imbi2i 225	. . . 4 ⊢ ((𝑥 = 𝑦 → [𝑤 / 𝑧]𝜑) ↔ (𝑥 = 𝑦 → ∀𝑧(𝑧 = 𝑤 → 𝜑)))
18	17	albii 1463	. . 3 ⊢ (∀𝑥(𝑥 = 𝑦 → [𝑤 / 𝑧]𝜑) ↔ ∀𝑥(𝑥 = 𝑦 → ∀𝑧(𝑧 = 𝑤 → 𝜑)))
19	15, 18	bitri 183	. 2 ⊢ ([𝑦 / 𝑥][𝑤 / 𝑧]𝜑 ↔ ∀𝑥(𝑥 = 𝑦 → ∀𝑧(𝑧 = 𝑤 → 𝜑)))
20	9, 14, 19	3bitr4i 211	1 ⊢ ([𝑤 / 𝑧][𝑦 / 𝑥]𝜑 ↔ [𝑦 / 𝑥][𝑤 / 𝑧]𝜑)

Syntax hints:   → wi 4   ↔ wb 104  ∀wal 1346  [wsb 1755

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-5 1440  ax-7 1441  ax-gen 1442  ax-ie1 1486  ax-ie2 1487  ax-8 1497  ax-11 1499  ax-4 1503  ax-17 1519  ax-i9 1523  ax-ial 1527  ax-i5r 1528

This theorem depends on definitions:  df-bi 116  df-sb 1756

This theorem is referenced by:  sbcom2v2  1979