Timeline for Can one make a category concrete by "enlarging the universe"?
Current License: CC BY-SA 3.0
3 events
| when toggle format | what | by | license | comment | |
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| Apr 30, 2017 at 19:55 | comment | added | Ingo Blechschmidt | $\mathbf{Set}^\mathrm{op}$ is equivalent to the category of complete atomic Heyting algebras (you may read "complete atomic Boolean algebras" here, if you're willing to work in classical logic) and therefore concrete as a subcategory of a concrete category. | |
| Dec 13, 2014 at 6:13 | comment | added | Zhen Lin | In fact, $\mathbf{Set}^\mathrm{op}$ and $\mathbf{Rel}$ are concrete. First, note that the former embeds in the latter in an obvious way. Then note that $\mathbf{Rel}$ can be embedded in $\mathbf{Set}$ by sending each set $X$ to $2^X$. | |
| Dec 13, 2014 at 0:52 | history | answered | Anton Fetisov | CC BY-SA 3.0 |