Theorem elpri

Description: If a class is an element of a pair, then it is one of the two paired elements. (Contributed by Scott Fenton, 1-Apr-2011)

	Ref	Expression
Assertion	elpri	|- ( A e. { B , C } -> ( A = B \/ A = C ) )

Proof

Step	Hyp	Ref	Expression
1		elprg	|- ( A e. { B , C } -> ( A e. { B , C } <-> ( A = B \/ A = C ) ) )
2	1	ibi	|- ( A e. { B , C } -> ( A = B \/ A = C ) )