Metamath Proof Explorer


Theorem bi23impib

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

Ref Expression
Hypothesis bi23impib.1 φ ψ χ θ
Assertion bi23impib φ ψ χ θ

Proof

Step Hyp Ref Expression
1 bi23impib.1 φ ψ χ θ
2 1 biimpd φ ψ χ θ
3 2 3impib φ ψ χ θ