Timeline for Is reflection on Grothendieck universes equivalent to TG set theory?
Current License: CC BY-SA 4.0
6 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Aug 24 at 21:31 | comment | added | Asaf Karagila♦ | @ZuhairAl-Johar: Proof from what theory? | |
| Aug 24 at 9:08 | comment | added | Asaf Karagila♦ | @ZuhairAl-Johar: What exactly do you mean? | |
| Aug 23 at 9:06 | comment | added | Zuhair Al-Johar | @AndreasBlass, if $\operatorname {unv}(V_\alpha)$, then $\alpha$ must be regular, otherwise there would be a cofinal subset of $\alpha$ that is hereditarily strictly subnumerous to $V_\alpha$ and thus must be an element of $V_\alpha$ which cannot be. I think the point lies in the definition of "hereditarily". I've added a clarification about what I meant by it. | |
| Aug 22 at 19:16 | comment | added | Andreas Blass | Note that the definition of unv in the question doesn't require $\alpha$ to be regular. In view of the question about TG, it's reasonable to suppose that regularity was intended, but as currently defined, unv is quite weak, and the proposed reflection schema seems to be provable in ZFC. | |
| Aug 22 at 18:02 | vote | accept | Zuhair Al-Johar | ||
| Aug 22 at 17:22 | history | answered | Asaf Karagila♦ | CC BY-SA 4.0 |