标题： 实数轴上的扩展-收缩可塑性 显示英文标题

标题： Expand-contract plasticity on the real line

摘要： 文章讨论了实数线$A$上的塑料和非塑料子空间${\mathbb{R}}$，以及通常的欧几里得度量$d$。 它研究了非扩张双射，证明了这类映射的性质，并通过例子展示了它们的相关性。 最后，证明了子空间$A$的可塑性属性至少包含两个互补的问题，一个纯粹几何问题和一个拓扑问题。 两者都对可塑性属性提供了重要的方面，并在高维和更抽象的度量空间中变得更加关键。 显示英文摘要

摘要： The article deals with plastic and non-plastic sub-spaces $A$ of the real line ${\mathbb{R}}$ with the usual Euclidean metric $d$. It investigates non-expansive bijections, proves properties of such maps and demonstrates their relevance by hands of examples. Finally, it is shown that the plasticity property of a sub-space $A$ contains at least two complementary questions, a purely geometric and a topological one. Both contribute essential aspects to the plasticity property and get more critical in higher dimensions and more abstract metric spaces.