Two metrics dd and dd' on a set XX are equivalent if they induce the same on XX.

Equivalent characterizations

Equivalently, idX:(X,d)(X,d)\operatorname{id}_X:(X,d)\to(X,d') is a .

Remarks

Equivalent metrics have the same open sets and therefore the same convergent sequences, but they may differ in which sequences are and whether the space is .

Examples
  • For any metric dd, the bounded metric d(x,y)=min{1,d(x,y)}d'(x,y)=\min\{1,d(x,y)\} is equivalent to dd.
  • On Rn\mathbb R^n, the Euclidean and taxicab metrics are equivalent.