Timeline for "At most one" versus "at most finitely many"
Current License: CC BY-SA 4.0
7 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Dec 20, 2022 at 16:21 | vote | accept | Sam Sanders | ||
| Nov 23, 2022 at 14:45 | comment | added | Tim Campion | Is $|w|$ fixed here, or not? That is, should I read $(\ast)$ as saying $$(\exists l) (\forall n)(\exists w : [0,l-1] \to \mathbb N) (\forall X)\Bigl[\varphi(X, n)\rightarrow (\exists i< l )(X=w(i))\Bigr]\tag{*1}$$ or should I rather read it as saying $$(\forall n)(\exists l) (\exists w : [0,l-1] \to \mathbb N) (\forall X)\Bigl[\varphi(X, n)\rightarrow (\exists i< l )(X=w(i))\Bigr]\tag{*2}$$? (In either case I assume some coding is used to talk about having a function $w : [0,l-1] \to \mathbb N$.) | |
| Nov 23, 2022 at 11:19 | answer | added | Sam Sanders | timeline score: 4 | |
| Nov 20, 2022 at 17:56 | history | edited | LSpice | CC BY-SA 4.0 |
Name of reference; TeX -> Unicode quotes; `\label`+`\eqref`
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| Nov 20, 2022 at 14:31 | comment | added | Andreas Blass | Another related phenomenon, which is classical and may have motivated the question, is that finite-to-one, or even countable-to-one, projections of Borel sets are Borel. | |
| Nov 20, 2022 at 14:08 | comment | added | Joel David Hamkins | A related phenomenon is the fact in set theory that a set is hereditarily ordinal definable if and only if it is hereditarily ordinal algebraic. (Algebraic means that the object has a property that only finitely many objects have.) See dx.doi.org/10.1215/00294527-3542326 | |
| Nov 20, 2022 at 11:12 | history | asked | Sam Sanders | CC BY-SA 4.0 |