Theorem dftru2

An alternate definition of "true" (see comment of [df-tru] ). The associated justification theorem is monothetic. (Contributed by Anthony Hart, 13-Oct-2010.) (Revised by BJ, 12-Jul-2019.) Use tru instead. (New usage is discouraged.)

Conclusion
\( \vdash \top \leftrightarrow \varphi \rightarrow \varphi \)
Proof
l0
tru
id
2th l0 _