Theorem trut

Description: A proposition is equivalent to it being implied by T. . Closed form of mptru . Dual of dfnot . It is to tbtru what a1bi is to tbt . (Contributed by BJ, 26-Oct-2019)

	Ref	Expression
Assertion	trut	$$⊢\phi \leftrightarrow \left(\top \to \phi \right)$$

Proof

Step	Hyp	Ref	Expression
1		tru	$$⊢\top$$
2	1	a1bi	$$⊢\phi \leftrightarrow \left(\top \to \phi \right)$$