Let (X, ρ) be a metric space and ↓USCC(X) and ↓CC(X) be the families of the regions below all upper semi-continuous compact-supported maps and below all continuous compact-supported maps from X to I = [0,1], respec...Let (X, ρ) be a metric space and ↓USCC(X) and ↓CC(X) be the families of the regions below all upper semi-continuous compact-supported maps and below all continuous compact-supported maps from X to I = [0,1], respectively. With the Hausdorff-metric, they are topological spaces. In this paper, we prove that, if X is an infinite compact metric space with a dense set of isolated points, then (↓USCC(X), ↓CC(X)) ≈ (Q, c 0 ∪ (Q Σ)), i.e., there is a homeomorphism h:↓USCC(X) → Q such that h(↓CC(X)) = c 0 ∪ (Q Σ), where Q = [?1,1]ω, Σ = {(x n ) n∈? ∈ Q: sup|x n | < 1} and c 0 = {(x n ) n∈? ∈ Σ: lim n→+∞ x n = 0}. Combining this statement with a result in our previous paper, we have $$ ( \downarrow USCC(X), \downarrow CC(X)) \approx \left\{ \begin{gathered} (Q,c_0 \cup (Q\backslash \Sigma )), if the set of isolanted points is dense in X, \hfill \\ (Q,c_0 ),otherwise, \hfill \\ \end{gathered} \right. $$ if X is an infinite compact metric space. We also prove that, for a metric space X, (↓USCC(X), ↓CC(X)) ≈ (Σ, c 0) if and only if X is non-compact, locally compact, non-discrete and separable.展开更多
基金supported by National Natural Science Foundation of China (Grant No. 10471084)
文摘Let (X, ρ) be a metric space and ↓USCC(X) and ↓CC(X) be the families of the regions below all upper semi-continuous compact-supported maps and below all continuous compact-supported maps from X to I = [0,1], respectively. With the Hausdorff-metric, they are topological spaces. In this paper, we prove that, if X is an infinite compact metric space with a dense set of isolated points, then (↓USCC(X), ↓CC(X)) ≈ (Q, c 0 ∪ (Q Σ)), i.e., there is a homeomorphism h:↓USCC(X) → Q such that h(↓CC(X)) = c 0 ∪ (Q Σ), where Q = [?1,1]ω, Σ = {(x n ) n∈? ∈ Q: sup|x n | < 1} and c 0 = {(x n ) n∈? ∈ Σ: lim n→+∞ x n = 0}. Combining this statement with a result in our previous paper, we have $$ ( \downarrow USCC(X), \downarrow CC(X)) \approx \left\{ \begin{gathered} (Q,c_0 \cup (Q\backslash \Sigma )), if the set of isolanted points is dense in X, \hfill \\ (Q,c_0 ),otherwise, \hfill \\ \end{gathered} \right. $$ if X is an infinite compact metric space. We also prove that, for a metric space X, (↓USCC(X), ↓CC(X)) ≈ (Σ, c 0) if and only if X is non-compact, locally compact, non-discrete and separable.
