(1864–1909), Russian-born German mathematician. He worked on the properties of sets in multidimensional systems, and suggested the concept of four-dimensional space–time, which was the basis for Einstein's general theory of relativity.
英汉双解词典包含464360条英汉词条，基本涵盖了全部常用单词的翻译及用法，是英语学习的有利工具。