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Limitation topologies on function spaces. (English) Zbl 0688.54008

For topological spaces X and Y denote the set of all continuous functions from X to Y by C(X,Y). For a function \(f\in C(X,Y)\) and a family \({\mathcal C}\) of subset of Y set \[ B(f,{\mathcal C})=\{g\in C(X,Y):\quad \{\{f(x),g(x)\}:\quad x\in X\quad refines\quad {\mathcal C}\}\}. \] Then \(\tau =\{U\subseteq C(X,Y):\) for all \(f\in U\) there is an open cover \({\mathcal C}\) of Y with B(f,\({\mathcal C})\subseteq U\}\) is a topology on C(X,Y) called the limitation topology. If “open cover of Y” in the above definition is replaced by “family of open subsets of Y which covers f(X)” one gets the modified limitation topology \(\tau '\). The author shows that \(\{\) B(f,\({\mathcal C}):\) \({\mathcal C}\) is an open cover of \(Y\}\) is a local base of \(\tau\) at \(f\in C(X,Y)\) if Y is paracompact, and consequently a subset \(E\subseteq C(X,Y)\) is \(\tau\)-dense in C(X,Y) if and only if B(f,\({\mathcal C})\cap E\neq \emptyset\) for all f and all \({\mathcal C}\). An analogous result is proven for \(\tau '\). Furthermore, if X is compact, metrizable and Y metrizable then \(\tau\) and \(\tau '\) are equal to the compact-open topology. Two more related topologies are defined and the question of whether they coincide is discussed.
Reviewer: H.-P.Butzmann

MSC:

54C35 Function spaces in general topology
54A10 Several topologies on one set (change of topology, comparison of topologies, lattices of topologies)
Full Text: DOI

References:

[1] Czesław Bessaga and Aleksander Pełczyński, Selected topics in infinite-dimensional topology, PWN — Polish Scientific Publishers, Warsaw, 1975. Monografie Matematyczne, Tom 58. [Mathematical Monographs, Vol. 58]. · Zbl 0304.57001
[2] James Dugundji, Topology, Allyn and Bacon, Inc., Boston, Mass., 1966. · Zbl 0144.21501
[3] R. A. McCoy, Fine topology on function spaces, Internat. J. Math. Math. Sci. 9 (1986), no. 3, 417 – 424. · Zbl 0614.54014 · doi:10.1155/S0161171286000534
[4] R. A. McCoy, The open-cover topology on function spaces, Fund. Math. 104 (1979), no. 2, 69 – 73. · Zbl 0432.54012
[5] H. Toruńczyk, On \?\?-images of the Hilbert cube and characterization of \?-manifolds, Fund. Math. 106 (1980), no. 1, 31 – 40. · Zbl 0346.57004
[6] H. Toruńczyk, Characterizing Hilbert space topology, Fund. Math. 111 (1981), no. 3, 247 – 262. · Zbl 0468.57015
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