Metamath Proof Explorer


Theorem bi13impib

Description: 3impib with the outer implication of the hypothesis a biconditional. (Contributed by Alan Sare, 6-Nov-2017)

Ref Expression
Hypothesis bi13impib.1 φ ψ χ θ
Assertion bi13impib φ ψ χ θ

Proof

Step Hyp Ref Expression
1 bi13impib.1 φ ψ χ θ
2 1 biimpi φ ψ χ θ
3 2 3impib φ ψ χ θ