Theorem truorfal 1607

Description: A ∨ identity. (Contributed by Anthony Hart, 22-Oct-2010.)

Assertion

Ref	Expression
truorfal	⊢ ((⊤ ∨ ⊥) ↔ ⊤)

Proof of Theorem truorfal

Step	Hyp	Ref	Expression
1		tru 1573	. . 3 ⊢ ⊤
2	1	orci 878	. 2 ⊢ (⊤ ∨ ⊥)
3	2	bitru 1578	1 ⊢ ((⊤ ∨ ⊥) ↔ ⊤)

This proof depends on syntax axioms:   ↔ wb 209   ∨ wo 860  ⊤wtru 1570  ⊥wfal 1581

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This proof depends on definitions:  df-bi 210  df-or 861  df-tru 1572

This theorem is used by:  trunorfal  1619