Theorem elimhyp3v 4575

Description: Eliminate a hypothesis containing 3 class variables. (Contributed by NM, 14-Aug-1999.)

Hypotheses

Ref	Expression
elimhyp3v.1	⊢ (𝐴 = if(𝜑, 𝐴, 𝐷) → (𝜑 ↔ 𝜒))
elimhyp3v.2	⊢ (𝐵 = if(𝜑, 𝐵, 𝑅) → (𝜒 ↔ 𝜃))
elimhyp3v.3	⊢ (𝐶 = if(𝜑, 𝐶, 𝑆) → (𝜃 ↔ 𝜏))
elimhyp3v.4	⊢ (𝐷 = if(𝜑, 𝐴, 𝐷) → (𝜂 ↔ 𝜁))
elimhyp3v.5	⊢ (𝑅 = if(𝜑, 𝐵, 𝑅) → (𝜁 ↔ 𝜎))
elimhyp3v.6	⊢ (𝑆 = if(𝜑, 𝐶, 𝑆) → (𝜎 ↔ 𝜏))
elimhyp3v.7	⊢ 𝜂

Assertion

Ref	Expression
elimhyp3v	⊢ 𝜏

Proof of Theorem elimhyp3v

Step	Hyp	Ref	Expression
1		iftrue 4513	. . . . . 6 ⊢ (𝜑 → if(𝜑, 𝐴, 𝐷) = 𝐴)
2	1	eqcomd 2740	. . . . 5 ⊢ (𝜑 → 𝐴 = if(𝜑, 𝐴, 𝐷))
3		elimhyp3v.1	. . . . 5 ⊢ (𝐴 = if(𝜑, 𝐴, 𝐷) → (𝜑 ↔ 𝜒))
4	2, 3	syl 17	. . . 4 ⊢ (𝜑 → (𝜑 ↔ 𝜒))
5		iftrue 4513	. . . . . 6 ⊢ (𝜑 → if(𝜑, 𝐵, 𝑅) = 𝐵)
6	5	eqcomd 2740	. . . . 5 ⊢ (𝜑 → 𝐵 = if(𝜑, 𝐵, 𝑅))
7		elimhyp3v.2	. . . . 5 ⊢ (𝐵 = if(𝜑, 𝐵, 𝑅) → (𝜒 ↔ 𝜃))
8	6, 7	syl 17	. . . 4 ⊢ (𝜑 → (𝜒 ↔ 𝜃))
9		iftrue 4513	. . . . . 6 ⊢ (𝜑 → if(𝜑, 𝐶, 𝑆) = 𝐶)
10	9	eqcomd 2740	. . . . 5 ⊢ (𝜑 → 𝐶 = if(𝜑, 𝐶, 𝑆))
11		elimhyp3v.3	. . . . 5 ⊢ (𝐶 = if(𝜑, 𝐶, 𝑆) → (𝜃 ↔ 𝜏))
12	10, 11	syl 17	. . . 4 ⊢ (𝜑 → (𝜃 ↔ 𝜏))
13	4, 8, 12	3bitrd 305	. . 3 ⊢ (𝜑 → (𝜑 ↔ 𝜏))
14	13	ibi 267	. 2 ⊢ (𝜑 → 𝜏)
15		elimhyp3v.7	. . 3 ⊢ 𝜂
16		iffalse 4516	. . . . . 6 ⊢ (¬ 𝜑 → if(𝜑, 𝐴, 𝐷) = 𝐷)
17	16	eqcomd 2740	. . . . 5 ⊢ (¬ 𝜑 → 𝐷 = if(𝜑, 𝐴, 𝐷))
18		elimhyp3v.4	. . . . 5 ⊢ (𝐷 = if(𝜑, 𝐴, 𝐷) → (𝜂 ↔ 𝜁))
19	17, 18	syl 17	. . . 4 ⊢ (¬ 𝜑 → (𝜂 ↔ 𝜁))
20		iffalse 4516	. . . . . 6 ⊢ (¬ 𝜑 → if(𝜑, 𝐵, 𝑅) = 𝑅)
21	20	eqcomd 2740	. . . . 5 ⊢ (¬ 𝜑 → 𝑅 = if(𝜑, 𝐵, 𝑅))
22		elimhyp3v.5	. . . . 5 ⊢ (𝑅 = if(𝜑, 𝐵, 𝑅) → (𝜁 ↔ 𝜎))
23	21, 22	syl 17	. . . 4 ⊢ (¬ 𝜑 → (𝜁 ↔ 𝜎))
24		iffalse 4516	. . . . . 6 ⊢ (¬ 𝜑 → if(𝜑, 𝐶, 𝑆) = 𝑆)
25	24	eqcomd 2740	. . . . 5 ⊢ (¬ 𝜑 → 𝑆 = if(𝜑, 𝐶, 𝑆))
26		elimhyp3v.6	. . . . 5 ⊢ (𝑆 = if(𝜑, 𝐶, 𝑆) → (𝜎 ↔ 𝜏))
27	25, 26	syl 17	. . . 4 ⊢ (¬ 𝜑 → (𝜎 ↔ 𝜏))
28	19, 23, 27	3bitrd 305	. . 3 ⊢ (¬ 𝜑 → (𝜂 ↔ 𝜏))
29	15, 28	mpbii 233	. 2 ⊢ (¬ 𝜑 → 𝜏)
30	14, 29	pm2.61i 182	1 ⊢ 𝜏

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 206   = wceq 1539  ifcif 4507

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1794  ax-4 1808  ax-5 1909  ax-6 1966  ax-7 2006  ax-8 2109  ax-9 2117  ax-ext 2706

This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-ex 1779  df-sb 2064  df-clab 2713  df-cleq 2726  df-clel 2808  df-if 4508

This theorem is referenced by:  sseliALT  5291