Description: Two self-implications (see id ) are equivalent. This theorem, rather
trivial in our axiomatization, is (the biconditional form of) a standard
axiom for monothetic BCI logic. This is the most general theorem of which
trujust is an instance. Relatedly, this would be the justification
theorem if the definition of T. were dftru2 . (Contributed by BJ, 7-Sep-2022)