Definition:P-Product Metric

Definition
Let $M_{1'} = \left({A_{1'}, d_{1'}}\right)$ and $M_{2'} = \left({A_{2'}, d_{2'}}\right)$ be metric spaces.

Let $A_{1'} \times A_{2'}$ be the cartesian product of $A_{1'}$ and $A_{2'}$.

Let $p \in \R_{\ge 1}$.

The $p$-product metric on $A_{1'} \times A_{2'}$ is defined as:
 * $d_p \left({x, y}\right) := \left({\left({d_{1'} \left({x_1, y_1}\right)}\right)^p + \left({d_{2'} \left({x_2, y_2}\right)}\right)^p}\right)^{1/p}$

where $x = \left({x_1, x_2}\right), y = \left({y_1, y_2}\right) \in A_{1'} \times A_{2'}$.

The metric space $\mathcal M_p := \left({A_{1'} \times A_{2'}, d_p}\right)$ is the $p$-product (space) of $M_{1'}$ and $M_{2'}$.

Real Number Plane
This metric is often found in the context of a real number plane $\R^2$:

General Definition
The definition can be extended to the cartesian product of any finite number $n$ of metric spaces.

Special Cases
Some special cases of the $p$-product metric are:

Also see

 * $p$-Product Metric is Metric

Notation
The notation is awkward, because it is necessary to use a indexing subscript for the $n$ metric spaces contributing to the product, and also for the $p$th exponential that defines the metric itself.

Thus the "prime" notation on the $n$ metric spaces.