Let X and Y be metric compacta such that there exists a continuous open surjection from $C_p(Y)$ onto $C_p(X)$. We prove that if there exists an integer k such that $X^k$ is strongly infinite-dimensional, then there exists an integer p such that $Y^p$ is strongly infinite-dimensional.
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We construct two examples of infinite spaces X such that there is no continuous linear surjection from the space of continuous functions $c_p(X)$ onto $c_p(X)$ × ℝ$. In particular, $c_p(X)$ is not linearly homeomorphic to $c_p(X)$ × ℝ$. One of these examples is compact. This answers some questions of Arkhangel'skiĭ.
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We prove that for each countably infinite, regular space X such that $C_p(X)$ is a $Z_σ$-space, the topology of $C_p(X)$ is determined by the class $F_0(C_p(X))$ of spaces embeddable onto closed subsets of $C_p(X)$. We show that $C_p(X)$, whenever Borel, is of an exact multiplicative class; it is homeomorphic to the absorbing set $Ω_α$ for the multiplicative Borel class $M_α$ if $F_0(C_p(X)) = M_α$. For each ordinal α ≥ 2, we provide an example $X_α$ such that $C_p(X_α)$ is homeomorphic to $Ω_α$.
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"Near metric" properties of the space of continuous real-valued functions on a space X with the compact-open topology or with the topology of pointwise convergence are examined. In particular, it is investigated when these spaces are stratifiable or cometrisable.
CONTENTS Introduction.......................................................................................................... 5 1. Multifunctions and selections............................................................................... 7 1. Multifunctions and selections.................................................................. 7 2. Continuous multifunctions and selections........................................... 9 3. Measurable multifunctions and selections............................................ 16 2. Multifunctions of two variables............................................................................... 19 4. Carathéodory multifunctions and selections......................................... 19 5. The Scorza Dragoni property..................................................................... 25 6. Implicit function theorems......................................................................... 32 3. The superposition operator................................................................................... 33 7. The superposition operator in the space S........................................... 34 8. The superposition operator in ideal spaces......................................... 39 9. The superposition operator in the space C........................................... 47 4. Closures and convexifications.............................................................................. 49 10. Strong closures........................................................................................ 49 11. Convexifications....................................................................................... 52 12. Weak closures.......................................................................................... 56 5. Fixed points and integral inclusions..................................................................... 59 13. Fixed point theorems for multi-valued operators................................ 60 14. Hammerstein integral inclusions........................................................ 63 15. A reduction method................................................................................... 68 6. Applications............................................................................................................... 72 16. Applications to elliptic systems.............................................................. 72 17. Applications to nonlinear oscillations................................................. 75 18. Applications to relay problems.............................................................. 78 References.................................................................................................................... 81 Index of symbols........................................................................................................... 93 Index of terms................................................................................................................ 95
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