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Theorem truanOLD 1246
Description: Obsolete proof of truan 1245 as of 21-Jul-2019. (Contributed by FL, 20-Mar-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
truanOLD (( ⊤ φ) ↔ φ)

Proof of Theorem truanOLD
StepHypRef Expression
1 simpr 103 . 2 (( ⊤ φ) → φ)
2 a1tru 1244 . . 3 (φ → ⊤ )
32ancri 307 . 2 (φ → ( ⊤ φ))
41, 3impbii 117 1 (( ⊤ φ) ↔ φ)
Colors of variables: wff set class
Syntax hints:   wa 97  wb 98  wtru 1229
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101
This theorem depends on definitions:  df-bi 110  df-tru 1231
This theorem is referenced by: (None)
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