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	|- ( ph <-> ( T. -> ph ) )

Proof

Step	Hyp	Ref	Expression
1		tru	|- T.
2	1	a1bi	|- ( ph <-> ( T. -> ph ) )