Theorem tbtru

Description: A proposition is equivalent to itself being equivalent to T. . (Contributed by Anthony Hart, 14-Aug-2011)

	Ref	Expression
Assertion	tbtru	⊢ ( 𝜑 ↔ ( 𝜑 ↔ ⊤ ) )

Proof

Step	Hyp	Ref	Expression
1		tru	⊢ ⊤
2	1	tbt	⊢ ( 𝜑 ↔ ( 𝜑 ↔ ⊤ ) )