Math and science::Topology Metric space. ε-balls Let X be a metric space, let x∈X and let ε>0 be a real. The open ε-ball around x (or in more detail, the open ball around x of radius ε) is the subset of X given by [ B(x,ε)={y∈X:what condition?} ] Similarly, the closed ε-ball around x is [B¯(x,ε)={y∈X:what condition?} ] 14.05.2020