Theorem wl-equsal1i 35629

Description: The antecedent 𝑥 = 𝑦 is irrelevant, if one or both setvar variables are not free in 𝜑. (Contributed by Wolf Lammen, 1-Sep-2018.)

Hypotheses

Ref	Expression
wl-equsal1i.1	⊢ (Ⅎ𝑥𝜑 ∨ Ⅎ𝑦𝜑)
wl-equsal1i.2	⊢ (𝑥 = 𝑦 → 𝜑)

Assertion

Ref	Expression
wl-equsal1i	⊢ 𝜑

Proof of Theorem wl-equsal1i

Step	Hyp	Ref	Expression
1		wl-equsal1i.1	. 2 ⊢ (Ⅎ𝑥𝜑 ∨ Ⅎ𝑦𝜑)
2		wl-equsal1i.2	. . 3 ⊢ (𝑥 = 𝑦 → 𝜑)
3	2	gen2 1800	. 2 ⊢ ∀𝑥∀𝑦(𝑥 = 𝑦 → 𝜑)
4		sp 2178	. . . . 5 ⊢ (∀𝑦∀𝑥(𝑥 = 𝑦 → 𝜑) → ∀𝑥(𝑥 = 𝑦 → 𝜑))
5	4	alcoms 2157	. . . 4 ⊢ (∀𝑥∀𝑦(𝑥 = 𝑦 → 𝜑) → ∀𝑥(𝑥 = 𝑦 → 𝜑))
6		wl-equsal1t 35627	. . . 4 ⊢ (Ⅎ𝑥𝜑 → (∀𝑥(𝑥 = 𝑦 → 𝜑) ↔ 𝜑))
7	5, 6	syl5ib 243	. . 3 ⊢ (Ⅎ𝑥𝜑 → (∀𝑥∀𝑦(𝑥 = 𝑦 → 𝜑) → 𝜑))
8		wl-equsalcom 35628	. . . . 5 ⊢ (∀𝑦(𝑦 = 𝑥 → 𝜑) ↔ ∀𝑦(𝑥 = 𝑦 → 𝜑))
9		wl-equsal1t 35627	. . . . . 6 ⊢ (Ⅎ𝑦𝜑 → (∀𝑦(𝑦 = 𝑥 → 𝜑) ↔ 𝜑))
10	9	biimpd 228	. . . . 5 ⊢ (Ⅎ𝑦𝜑 → (∀𝑦(𝑦 = 𝑥 → 𝜑) → 𝜑))
11	8, 10	syl5bir 242	. . . 4 ⊢ (Ⅎ𝑦𝜑 → (∀𝑦(𝑥 = 𝑦 → 𝜑) → 𝜑))
12	11	spsd 2182	. . 3 ⊢ (Ⅎ𝑦𝜑 → (∀𝑥∀𝑦(𝑥 = 𝑦 → 𝜑) → 𝜑))
13	7, 12	jaoi 853	. 2 ⊢ ((Ⅎ𝑥𝜑 ∨ Ⅎ𝑦𝜑) → (∀𝑥∀𝑦(𝑥 = 𝑦 → 𝜑) → 𝜑))
14	1, 3, 13	mp2 9	1 ⊢ 𝜑

Syntax hints:   → wi 4   ∨ wo 843  ∀wal 1537  Ⅎwnf 1787

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1799  ax-4 1813  ax-5 1914  ax-6 1972  ax-7 2012  ax-10 2139  ax-11 2156  ax-12 2173  ax-13 2372

This theorem depends on definitions:  df-bi 206  df-an 396  df-or 844  df-ex 1784  df-nf 1788

This theorem is referenced by: (None)