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Theorem dfvd3 41884
Description: Definition of a 3-hypothesis virtual deduction. (Contributed by Alan Sare, 14-Nov-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
dfvd3 ((   𝜑   ,   𝜓   ,   𝜒   ▶   𝜃   ) ↔ (𝜑 → (𝜓 → (𝜒𝜃))))

Proof of Theorem dfvd3
StepHypRef Expression
1 df-vd3 41883 . 2 ((   𝜑   ,   𝜓   ,   𝜒   ▶   𝜃   ) ↔ ((𝜑𝜓𝜒) → 𝜃))
2 df-3an 1091 . . . . 5 ((𝜑𝜓𝜒) ↔ ((𝜑𝜓) ∧ 𝜒))
32imbi1i 353 . . . 4 (((𝜑𝜓𝜒) → 𝜃) ↔ (((𝜑𝜓) ∧ 𝜒) → 𝜃))
4 impexp 454 . . . 4 ((((𝜑𝜓) ∧ 𝜒) → 𝜃) ↔ ((𝜑𝜓) → (𝜒𝜃)))
53, 4bitri 278 . . 3 (((𝜑𝜓𝜒) → 𝜃) ↔ ((𝜑𝜓) → (𝜒𝜃)))
6 impexp 454 . . 3 (((𝜑𝜓) → (𝜒𝜃)) ↔ (𝜑 → (𝜓 → (𝜒𝜃))))
75, 6bitri 278 . 2 (((𝜑𝜓𝜒) → 𝜃) ↔ (𝜑 → (𝜓 → (𝜒𝜃))))
81, 7bitri 278 1 ((   𝜑   ,   𝜓   ,   𝜒   ▶   𝜃   ) ↔ (𝜑 → (𝜓 → (𝜒𝜃))))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 209  wa 399  w3a 1089  (   wvd3 41880
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
This theorem depends on definitions:  df-bi 210  df-an 400  df-3an 1091  df-vd3 41883
This theorem is referenced by:  dfvd3i  41885  dfvd3ir  41886
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