Theorem 3orbi123d 1206

Description: Deduction joining 3 equivalences to form equivalence of disjunctions. (Contributed by NM, 20-Apr-1994.)

Hypotheses

Ref	Expression
bi3d.1	⊢ (𝜑 → (𝜓 ↔ 𝜒))
bi3d.2	⊢ (𝜑 → (𝜃 ↔ 𝜏))
bi3d.3	⊢ (𝜑 → (𝜂 ↔ 𝜁))

Assertion

Ref	Expression
3orbi123d	⊢ (𝜑 → ((𝜓 ∨ 𝜃 ∨ 𝜂) ↔ (𝜒 ∨ 𝜏 ∨ 𝜁)))

Proof of Theorem 3orbi123d

Step	Hyp	Ref	Expression
1		bi3d.1	. . . 4 ⊢ (𝜑 → (𝜓 ↔ 𝜒))
2		bi3d.2	. . . 4 ⊢ (𝜑 → (𝜃 ↔ 𝜏))
3	1, 2	orbi12d 707	. . 3 ⊢ (𝜑 → ((𝜓 ∨ 𝜃) ↔ (𝜒 ∨ 𝜏)))
4		bi3d.3	. . 3 ⊢ (𝜑 → (𝜂 ↔ 𝜁))
5	3, 4	orbi12d 707	. 2 ⊢ (𝜑 → (((𝜓 ∨ 𝜃) ∨ 𝜂) ↔ ((𝜒 ∨ 𝜏) ∨ 𝜁)))
6		df-3or 886	. 2 ⊢ ((𝜓 ∨ 𝜃 ∨ 𝜂) ↔ ((𝜓 ∨ 𝜃) ∨ 𝜂))
7		df-3or 886	. 2 ⊢ ((𝜒 ∨ 𝜏 ∨ 𝜁) ↔ ((𝜒 ∨ 𝜏) ∨ 𝜁))
8	5, 6, 7	3bitr4g 212	1 ⊢ (𝜑 → ((𝜓 ∨ 𝜃 ∨ 𝜂) ↔ (𝜒 ∨ 𝜏 ∨ 𝜁)))

Syntax hints:   → wi 4   ↔ wb 98   ∨ wo 629   ∨ w3o 884

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-io 630

This theorem depends on definitions:  df-bi 110  df-3or 886

This theorem is referenced by:  ordtriexmid  4247  wetriext  4301  nntri3or  6072  ltsopi  6418  pitri3or  6420  nqtri3or  6494  elz  8247  ztri3or  8288  qtri3or  9098