资料来源 : Free On-Line Dictionary of Computing

normed space
     
         A {vector space} with a {function}, ||F||, such
        that
     
         ||F|| = 0 if and only if F=0
         ||aF|| = abs(a) * ||F||
         ||F+G|| <= ||F|| + ||G||
     
        Roughly, a distance between two elements in the space is
        defined.
     
        (2000-03-10)