Metamath Proof Explorer


Theorem opelxpi

Description: Ordered pair membership in a Cartesian product (implication). (Contributed by NM, 28-May-1995)

Ref Expression
Assertion opelxpi ACBDABC×D

Proof

Step Hyp Ref Expression
1 opelxp ABC×DACBD
2 1 biimpri ACBDABC×D