homotopy of mappings

例句：

1. 1. In mathematics,the homotopy group of a spaceis the set of all continuous maps fromthe space to itself.
   在数学中，一个空间的同伦群是所有从该空间到自身的连续映射的集合。
2. 2. The study of homotopy groupshas led to important advances in computergraphics and robotics.
   研究同伦群对计算机图形学和机器人学的发展产生了重要影响。
3. 3. The concept of homotopy plays a crucial role in the theoryof relativity.
   同伦概念在相对论理论中起着至关重要的作用。