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Theorem tbtru 1324
Description: If something is true, it outputs . (Contributed by Anthony Hart, 14-Aug-2011.)
Assertion
Ref Expression
tbtru (φ ↔ (φ ↔ ⊤ ))

Proof of Theorem tbtru
StepHypRef Expression
1 tru 1321 . 2
21tbt 333 1 (φ ↔ (φ ↔ ⊤ ))
Colors of variables: wff setvar class
Syntax hints:  wb 176  wtru 1316
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  df-tru 1319
This theorem is referenced by: (None)
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