Theorem
Letandbe open balls in a metric spaceand letthen a ball open inexists such that
Proof
LetandSupposeso there exists
Sincethere exists an open balland sincethere exists an open ball
Takethenandso
Theorem
Letandbe open balls in a metric spaceand letthen a ball open inexists such that
Proof
LetandSupposeso there exists
Sincethere exists an open balland sincethere exists an open ball
Takethenandso