Lebl-Basic-Analysis-I · Problem 7.5.7

Metric Spaces

Mathematics · continuous-functions

Problem

A continuous f ⁣:X→Yf \colon X \to Y between metric spaces (X,dX)(X, d_X) and (Y,dY)(Y, d_Y) is said to be proper if for every compact set K⊂YK \subset Y, the set f−1(K)f^{-1}(K) is compact. Suppose a continuous f ⁣:(0,1)→(0,1)f \colon (0, 1) \to (0, 1) is proper and {xn}n=1∞\{x_n\}_{n=1}^\infty is a sequence in (0,1)(0, 1) converging to 00. Show that {f(xn)}n=1∞\bigl\{f(x_n)\bigr\}_{n=1}^\infty has no subsequence that converges in (0,1)(0, 1).

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