or-false

Theorem.

Arguments:

phi (pr), psi (pr),

Assertions:

(lnotphito(psileftrightarrow(phiveepsi)))

Proof:

Hyp Ref Line Expr
im-true1(lnotphito(psileftrightarrow(lnotphitopsi)))
df-or2((phiveepsi)leftrightarrow(lnotphitopsi))
1, 2rpb33<>3(lnotphito(psileftrightarrow(phiveepsi)))