Timeline for What is the smallest $\sigma$-algebra of reals that is closed under addition of sets?
Current License: CC BY-SA 4.0
6 events
| when toggle format | what | by | license | comment | |
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| Nov 21, 2021 at 16:03 | comment | added | Alessandro Codenotti | That seems like a very good guess @Wojowu, let's see if I can work out the details | |
| Nov 19, 2021 at 13:15 | comment | added | Wojowu | I might be going off of a wild guess, but I suspect an argument like the one here might be able to get that in appropriate sense such sets are closed under projections. This way perhaps one can show this class is equal to the class of $\sigma$-projective sets. | |
| Nov 19, 2021 at 13:13 | comment | added | Gerald Edgar | If you start with the open sets, then generate using sigma-algebra operations and sums, do you get at least all the analytic sets? | |
| Nov 19, 2021 at 11:09 | comment | added | Emil Jeřábek | I take it the trivial upper bound is $\mathbf{\Delta}^2_1$? | |
| Nov 19, 2021 at 10:59 | history | edited | Alessandro Codenotti | CC BY-SA 4.0 |
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| Nov 19, 2021 at 10:04 | history | asked | Alessandro Codenotti | CC BY-SA 4.0 |