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Theorem trujust 1318
Description: Soundness justification theorem for df-tru 1319. (Contributed by Mario Carneiro, 17-Nov-2013.)
Assertion
Ref Expression
trujust ((φφ) ↔ (ψψ))

Proof of Theorem trujust
StepHypRef Expression
1 biid 227 . 2 (φφ)
2 biid 227 . 2 (ψψ)
31, 22th 230 1 ((φφ) ↔ (ψψ))
Colors of variables: wff setvar class
Syntax hints:  wb 176
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 177
This theorem is referenced by: (None)
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