例句與造句

1. Or maybe there is a reasonable classification for compact countable spaces?
2. Every first-countable space is a Fr閏het Urysohn space.
3. Thus, limits in first-countable spaces can be described by sequences.
4. Any second-countable space is a Lindel鰂 space, but not conversely.
5. They are the coreflective hull of all countable spaces.
6. It's difficult to find countable space in a sentence. 用countable space造句挺難的
7. Every second-countable space is first-countable, separable, and Lindel鰂.
8. This is a countable space, and it does not have the discrete topology.
9. So, I have studied both of the articles Lindel鰂 space and Second-countable space.
10. It seems that for countable spaces, T2 is still quite a wild class, right?
11. Specifically, every second-countable space is Lindel鰂 ( every open cover has a countable subcover ).
12. Every product of a first-countable space is first-countable, although uncountable products need not be.
13. So, why shouldn't it be possible to do calculus on a locally contractible first countable space?
14. Seperable, first countable spaces that are not Lindelof are easy to find ( for instance the Sorgenfrey plane ).
15. Every first-countable space is sequential, hence each second countable, metric space, and discrete space is sequential.
16. Every second-countable space is first-countable, but any uncountable discrete space is first-countable but not second-countable.
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