Timeline for What are the "smallest" topoi?
Current License: CC BY-SA 4.0
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| when toggle format | what | by | license | comment | |
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| Sep 22, 2018 at 19:12 | vote | accept | user14120 | ||
| Sep 22, 2018 at 12:32 | comment | added | Andreas Blass | Instead of applying Löwenheim-Skolem to ZF, you could apply it directly to topos theory: Every small topos has a countable elementary submodel. (And you can omit "small" if you work in a theory where satisfaction relations can be defined for proper-class models.) So, as far as first-order expressible (in the language of categories) properties are concerned, countable topoi can do everything that uncountable ones can. | |
| Sep 22, 2018 at 12:24 | history | answered | Simon Henry | CC BY-SA 4.0 |