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Theorem 3orbi123d 1217
 Description: Deduction joining 3 equivalences to form equivalence of disjunctions. (Contributed by NM, 20-Apr-1994.)
Hypotheses
Ref Expression
bi3d.1 (𝜑 → (𝜓𝜒))
bi3d.2 (𝜑 → (𝜃𝜏))
bi3d.3 (𝜑 → (𝜂𝜁))
Assertion
Ref Expression
3orbi123d (𝜑 → ((𝜓𝜃𝜂) ↔ (𝜒𝜏𝜁)))

Proof of Theorem 3orbi123d
StepHypRef Expression
1 bi3d.1 . . . 4 (𝜑 → (𝜓𝜒))
2 bi3d.2 . . . 4 (𝜑 → (𝜃𝜏))
31, 2orbi12d 717 . . 3 (𝜑 → ((𝜓𝜃) ↔ (𝜒𝜏)))
4 bi3d.3 . . 3 (𝜑 → (𝜂𝜁))
53, 4orbi12d 717 . 2 (𝜑 → (((𝜓𝜃) ∨ 𝜂) ↔ ((𝜒𝜏) ∨ 𝜁)))
6 df-3or 897 . 2 ((𝜓𝜃𝜂) ↔ ((𝜓𝜃) ∨ 𝜂))
7 df-3or 897 . 2 ((𝜒𝜏𝜁) ↔ ((𝜒𝜏) ∨ 𝜁))
85, 6, 73bitr4g 216 1 (𝜑 → ((𝜓𝜃𝜂) ↔ (𝜒𝜏𝜁)))
 Colors of variables: wff set class Syntax hints:   → wi 4   ↔ wb 102   ∨ wo 639   ∨ w3o 895 This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 103  ax-ia2 104  ax-ia3 105  ax-io 640 This theorem depends on definitions:  df-bi 114  df-3or 897 This theorem is referenced by:  ordtriexmid  4274  wetriext  4328  nntri3or  6102  ltsopi  6475  pitri3or  6477  nqtri3or  6551  elz  8303  ztri3or  8344  qtri3or  9199
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