Metamath Proof Explorer


Theorem expcomdg

Description: Biconditional form of expcomd . (Contributed by Alan Sare, 22-Jul-2012) (New usage is discouraged.)

Ref Expression
Assertion expcomdg φψχθφχψθ

Proof

Step Hyp Ref Expression
1 ancomst ψχθχψθ
2 impexp χψθχψθ
3 1 2 bitri ψχθχψθ
4 3 imbi2i φψχθφχψθ