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Metamath Proof Explorer


Theorem bi23imp13

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

Ref Expression
Hypothesis bi23imp13.1 φ ψ χ θ
Assertion bi23imp13 φ ψ χ θ

Proof

Step Hyp Ref Expression
1 bi23imp13.1 φ ψ χ θ
2 1 biimpd φ ψ χ θ
3 2 3imp φ ψ χ θ