>dford

Theorem.

Arguments:

phi (pr), psi (pr), chi (pr),

Hypotheses:

(phito(lnotpsitochi))

Assertions:

(phito(psiveechi))

Proof:

Hyp Ref Line Expr
Hypo1(phito(lnotpsitochi))
df-or2((psiveechi)leftrightarrow(lnotpsitochi))
1, 2brpi22<3(phito(psiveechi))