Theorem trubitru 1361

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

Step	Hyp	Ref	Expression
1		biid 170	. 2 ⊢ (⊤ ↔ ⊤)
2	1	bitru 1311	1 ⊢ ((⊤ ↔ ⊤) ↔ ⊤)

Syntax hints:   ↔ wb 104  ⊤wtru 1300

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 105  ax-ia2 106  ax-ia3 107

This theorem depends on definitions:  df-bi 116  df-tru 1302

This theorem is referenced by: (None)