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Oct 29, 2020 at 15:14 history edited Andrés E. Caicedo CC BY-SA 4.0
edited body
Oct 29, 2020 at 5:57 comment added Hanul Jeon @Noah Thank you for your comment. I fixed that part of my answer.
Oct 29, 2020 at 5:56 comment added Noah Schweber Again for the OP: to see that inaccessibility is not upwards absolute, consider forcings of the form $Col(\omega,\kappa)$ (say).
Oct 29, 2020 at 5:55 history edited Hanul Jeon CC BY-SA 4.0
Fix some error
Oct 29, 2020 at 5:46 comment added Noah Schweber +1. For the OP re: absoluteness: inaccessibility is more generally downwards absolute since it is a $\Pi_1$ property. All the "small" large cardinal properties (inaccessibility, Mahlo, weakly compact, ...) are similar. Things change drastically once we get to measurable cardinals: while to the best of our knowledge ZFC + "There is a measurable cardinal" is consistent, ZFC + V=L proves that there is no measurable cardinal. So measurability is not downwards-absolute: even if kappa is measurable in V, kappa won't be measurable in L.
Oct 29, 2020 at 5:32 history edited Hanul Jeon CC BY-SA 4.0
added 8 characters in body
S Oct 29, 2020 at 5:27 history answered Hanul Jeon CC BY-SA 4.0
S Oct 29, 2020 at 5:27 history made wiki Post Made Community Wiki by Hanul Jeon