for M being MetrSpace
for n being Nat
for F being Subset-Family of M
for p being FinSequence st F is being_ball-family & rng p = F & dom p = Seg (n + 1) holds
ex G being Subset-Family of M st
( G is finite & G is being_ball-family & ex q being FinSequence st
( rng q = G & dom q = Seg n & ex x being Point of M ex r being Real st union F c= (union G) \/ (Ball (x,r)) ) )