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... This property and its uniform version were researched in the study mentioned in the reference [5]. It says that any expansion of a distance between two points implies the existence of two other points which are contracted by the map ϕ. ...
The study deals with plastic and non-plastic sub-spaces A of the real-line 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.
It is known that if M is a finite-dimensional Banach space, or a strictly convex space, or the space , then every non-expansive bijection is an isometry. We extend these results to non-expansive bijections between unit balls of two different Banach spaces. Namely, if E is an arbitrary Banach space and M is finite-dimensional or strictly convex, or the space then every non-expansive bijection is an isometry.
We extend the result of B. Cascales et al. about expand-contract plasticity of the unit ball of strictly convex Banach space to those spaces whose unit sphere is the union of all its finite-dimensional polyhedral extreme subsets. We also extend the definition of expand-contract plasticity to uniform spaces and generalize the theorem on expand-contract plasticity of totally bounded metric spaces to this new setting.
In this paper we examine the properties of EC-plastic metric spaces, spaces which have the property that any noncontractive bijection from the space onto itself must be an isometry.
H Freudenthal
W Hurewicz
Dehnungen
Verkürzungen
Fund Isometrien
Jan 1936
120-122
H Freudenthal
W Hurewicz
Dehnungen
Verkürzungen
Fund Isometrien
H. Freudenthal, W. Hurewicz, Dehnungen, Verkürzungen, Isometrien, Fund.
Math. 26 (1936) 120-122.