Timeline for Is there a pair of non-isomorphic structures each of which is isomorphic to an ultrapower of the other?

9 events

when toggle format	what		by	license	comment
Nov 23, 2018 at 13:53	history	edited	Gabe Goldberg	CC BY-SA 4.0	deleted 17 characters in body
Nov 23, 2018 at 13:43	history	edited	Gabe Goldberg	CC BY-SA 4.0	deleted 491 characters in body
Nov 22, 2018 at 21:29	vote	accept	James E Hanson
Nov 22, 2018 at 17:25	comment	added	Gabe Goldberg		$V_{\kappa+2}^M = V_{\kappa+2}^{M_U}$ since the natural map $M_U \to M_Z \to M$ has critical point $j_U(\kappa)$. Since $V_\kappa^M = V_\kappa$, $V_{j_W(\kappa)}^{j_W(M)} = j_W(V^M_\kappa) = j_W(V_\kappa) = V_{j_W(\kappa)}^{M_W},$ which implies the second equality.
Nov 22, 2018 at 15:03	comment	added	Danielle Ulrich		Why is $(V_{\kappa+2})^M = (V_{\kappa+2})^{M_U}$ and why is $(V_{\kappa+2})^{M_W} = (V_{\kappa+2})^{j_W(M)}$?
Nov 21, 2018 at 17:19	comment	added	Andrés E. Caicedo		@Noah I suppose you would need an appropriate directed system of embeddings and then you would use directed limits.
Nov 21, 2018 at 16:40	comment	added	Noah Schweber		If you don't require $S$ to be a well-ordering, how do you iterate along it? (I vaguely recall hearing that one could do this, but I don't recall the details.)
Nov 21, 2018 at 16:33	history	edited	Gabe Goldberg	CC BY-SA 4.0	added 491 characters in body
Nov 21, 2018 at 15:54	history	answered	Gabe Goldberg	CC BY-SA 4.0