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Theorem trubitru 1350
Description: A identity. (Contributed by Anthony Hart, 22-Oct-2010.) (Proof shortened by Andrew Salmon, 13-May-2011.)
Assertion
Ref Expression
trubitru (( ⊤ ↔ ⊤ ) ↔ ⊤ )

Proof of Theorem trubitru
StepHypRef Expression
1 biid 227 . 2 ( ⊤ ↔ ⊤ )
21bitru 1326 1 (( ⊤ ↔ ⊤ ) ↔ ⊤ )
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:  truxortru  1358
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