Timeline for Is it true but unassertable that there are undefinable real numbers?
Current License: CC BY-SA 4.0
7 events
| when toggle format | what | by | license | comment | |
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| Jun 15 at 23:41 | comment | added | Keplerto | I'm not an expert, but there is another viewpoint that I like, a more constructivist one, to the real line. Not in ZFC, though. In my interpretation, there needs no be a concrete real number that is undefinable. In fact, the only way there could be one is if you constructed, and thus defined, it. Despite that, the real number line is never complete, as you can always diagonalize and get a new real number. Intuitively, even if an alphabet is countable, the subset that represents valid definitions of a real number is not. Constructivity not required, arxiv.org/pdf/0905.1677.pdf suffices. | |
| Apr 21 at 19:51 | review | Close votes | |||
| Apr 23 at 21:23 | |||||
| Apr 12 at 10:25 | vote | accept | user107952 | ||
| Apr 12 at 8:31 | comment | added | David Gao | There are pointwise definable models of ZFC. Not sure why you still think there are necessarily undefinable reals. In any case, you might be interested in my answer under a different question here: math.stackexchange.com/a/4852973/465145 | |
| Apr 12 at 8:15 | answer | added | Antares | timeline score: 3 | |
| Apr 11 at 22:00 | comment | added | Somos | Exactly why do you "think there are undefinable real numbers" in "reality"? | |
| Apr 11 at 21:47 | history | asked | user107952 | CC BY-SA 4.0 |