Theorem brrelex1i

Description: The first argument of a binary relation exists. (An artifact of our ordered pair definition.) (Contributed by NM, 4-Jun-1998)

	Ref	Expression
Hypothesis	brrelexi.1	|- Rel R
Assertion	brrelex1i	|- ( A R B -> A e. _V )

Proof

Step	Hyp	Ref	Expression
1		brrelexi.1	|- Rel R
2		brrelex1	|- ( ( Rel R /\ A R B ) -> A e. _V )
3	1 2	mpan	|- ( A R B -> A e. _V )