Metamath Proof Explorer


Theorem brxp

Description: Binary relation on a Cartesian product. (Contributed by NM, 22-Apr-2004)

Ref Expression
Assertion brxp A C × D B A C B D

Proof

Step Hyp Ref Expression
1 df-br A C × D B A B C × D
2 opelxp A B C × D A C B D
3 1 2 bitri A C × D B A C B D