Timeline for Characterisations of closed embeddings in $Top_1$?
Current License: CC BY-SA 3.0
6 events
| when toggle format | what | by | license | comment | |
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| Sep 22, 2015 at 18:50 | answer | added | Todd Trimble | timeline score: 9 | |
| Sep 22, 2015 at 18:46 | comment | added | user44591 | @Zhen Lin: I think all extremal monomorphisms are closed embeddings in Hausdorff spaces. If $f:X \rightarrow Y$ is an extremal mono ,consider $Z = \overline{f(X)}$ (the closure of the images) and let $g:X \rightarrow Z$ be the obvious map and $i: Z \rightarrow Y$ the inclusion. $g$ is an epi in the category of Hausdorff spaces,since it has dense image, so is an iso since f is supposed to be extremal. In the category of Hausdorff spaces, closed embeddings are regular monomorphisms, and since every regular monomorphism is extremal, the claim should follow. | |
| S Sep 22, 2015 at 18:17 | history | suggested | CommunityBot | CC BY-SA 3.0 |
Typo in title
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| Sep 22, 2015 at 18:05 | review | Suggested edits | |||
| S Sep 22, 2015 at 18:17 | |||||
| Sep 22, 2015 at 17:40 | review | First posts | |||
| Sep 22, 2015 at 18:29 | |||||
| Sep 22, 2015 at 17:35 | history | asked | Carlson | CC BY-SA 3.0 |