Timeline for Infinite time Turing machines, semi-decidable sets and descriptive set theory
Current License: CC BY-SA 4.0
10 events
| when toggle format | what | by | license | comment | |
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| Mar 2 at 15:16 | comment | added | Johan | What is a proof that the answer to Question 1 is positive when we drop the 'eventually'? | |
| Aug 3, 2021 at 21:47 | history | edited | Philip Welch |
Added tag
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| Jul 27, 2021 at 19:48 | history | edited | Philip Welch | CC BY-SA 4.0 |
Question 3 should not have been asked in its original form and is thus updated.
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| Jul 25, 2021 at 16:56 | history | edited | Philip Welch | CC BY-SA 4.0 |
Fixed spelling of title; added a final sentence concerning Merlin Carl's observation on the compatibility of Quests. 1 & 3.
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| Jul 24, 2021 at 7:02 | history | edited | YCor |
edited tags
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| Jul 23, 2021 at 7:55 | history | edited | Martin Sleziak | CC BY-SA 4.0 |
fixed font is probably not needed here
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| Jul 22, 2021 at 20:04 | comment | added | Philip Welch | @Noah: if $\omega_1^L$ is countable then somewhat trivially the union of the ev. semi-decidable thin sets is countable hence thin, since the ev.semi-decidable sets are provably $\Delta^1_2$, and hence, if thin, are all contained in $L$. But even that does not quite seem to say that that union is ev.semi-decidable itself (however the union is ev. semi-decidable in a constructible real parameter.) We could get rid of that param. if we knew every thin ev. semi-decid. set $A\subset F$, which the question about the singletons is a first step towards. | |
| Jul 22, 2021 at 19:18 | comment | added | Noah Schweber | I vaguely recall seeing a general theorem which in particular would give a positive answer to 2 under large cardinals (maybe in Martin's "The largest countable this, that, and the other") - does that sound plausible, or is my memory way off? | |
| Jul 22, 2021 at 16:43 | history | edited | YCor | CC BY-SA 4.0 |
formatting title
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| Jul 22, 2021 at 15:34 | history | asked | Philip Welch | CC BY-SA 4.0 |