Pseudometric space 伪度量
（重定向自Metric identification）
In mathematics, a pseudometric space or semi-metric space is a generalized metric space in which the distance between two distinct points can be zero. In the same way as every normed space is a metric space, every seminormed space is a pseudometric space. Because of this analogy the term semimetric space (which has a different meaning in topology) is sometimes used as a synonym, especially in functional analysis.
中任意元素
，若实值函数
符合以下三个条件，称它为一个伪度量（pseudometric）。
。