2bitr

Theorem.

Arguments:

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

Hypotheses:

(chileftrightarrowtheta)
(psileftrightarrowchi)
(phileftrightarrowpsi)

Assertions:

(phileftrightarrowtheta)

Proof:

Hyp Ref Line Expr
Hypo1(chileftrightarrowtheta)
2(psileftrightarrowchi)
3(phileftrightarrowpsi)
2, 3bitr4(phileftrightarrowchi)
1, 4bitr5(phileftrightarrowtheta)