Are there convenient subcategories of Top? |
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Authors: | Horst Herrlich |
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Institution: | Feldhaeuser Str. 69, 2804 Lilienthal, Fed. Rep. of Germany |
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Abstract: | The category Top has several pleasant properties but fails to have other desirable ones. Consequently there have been various attempts to replace Top by more convenient categories; mostly subcategories or supercategories of Top. Whereas several of the supercategories of Top have extremely pleasant properties, all the subcategories of Top investigated so far have some deficiencies. In the present article it is shown why this is so and why the search for more convenient subcategories of Top has to be in vain. As a preparation in Section 1 nine convenience-properties for topological categories are defined and their mutual relations are analyzed. In Section 2 it is shown that every topological subcategory of Top (under some minor, natural assumptions) it-with respect to each of the 9 mentioned properties-as convenient or inconvenient as Top itself. |
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Keywords: | 54B30 18B30 18D15 |
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