Metamath Proof Explorer


Theorem oprab4

Description: Two ways to state the domain of an operation. (Contributed by FL, 24-Jan-2010)

Ref Expression
Assertion oprab4 xyz|xyA×Bφ=xyz|xAyBφ

Proof

Step Hyp Ref Expression
1 opelxp xyA×BxAyB
2 1 anbi1i xyA×BφxAyBφ
3 2 oprabbii xyz|xyA×Bφ=xyz|xAyBφ