Timeline for When does a topos satisfy the axiom of regularity?
Current License: CC BY-SA 4.0
5 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Nov 3, 2020 at 15:59 | history | became hot network question | |||
| Nov 3, 2020 at 10:24 | vote | accept | Jordan Barrett | ||
| Nov 3, 2020 at 9:19 | answer | added | Andrej Bauer | timeline score: 22 | |
| Nov 3, 2020 at 8:02 | comment | added | Noah Schweber | I think it will take some work to whip up an appropriate phrasing of the axiom of regularity; "$\in$ is well-founded" isn't really categorical. One which I can think of - due to Hamkins as far as I know - is "If every well-founded set can be well-ordered, then every set can be well-ordered." But that's is extremely clunky to work with. (Incidentally, there are various questions here and at MSE about regularity in categorical foundations which may be of interest. | |
| Nov 3, 2020 at 7:51 | history | asked | Jordan Barrett | CC BY-SA 4.0 |