This paper discusses real functions preserving some values of distance, a representation theorem of (strongly) distance-a preserving maps on R is obtained, and it is proved that even a map on R which preserves infinitely many values of distance is not necessarily isometric.
本文讨论R上的保持某些距离值不变的映射,得到了R上(强)保a映射的表示定理,并证明了即使 在R上(强)保无穷多个距离值的映射也未必是等距的。