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Nov 7 at 16:09 comment added Zuhair Al-Johar @JoelDavidHamkins, I've further refined this definition to include $|A|=|\bigcup x|$ instead of $A=\bigcup x$, because singularity is a cardinality issue.
Nov 7 at 16:08 history edited Zuhair Al-Johar CC BY-SA 4.0
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Nov 6 at 15:39 history edited Zuhair Al-Johar CC BY-SA 4.0
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Nov 6 at 15:10 comment added Joel David Hamkins But with your edit, the definition is now not well defined, since the property depends on $x$ and not just on $\cup x$. What I had meant was for you to say that a set $A$ is supersingular, if there is an $x$ for which $A=\cup x$ and so forth.
Nov 6 at 4:47 comment added Zuhair Al-Johar @JoelDavidHamkins, thanks! I've edited.
Nov 6 at 4:46 history edited Zuhair Al-Johar CC BY-SA 4.0
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Nov 6 at 1:45 history became hot network question
Nov 5 at 22:56 comment added Joel David Hamkins To match the familiar terminology, one should have the adjectives "supersingular", "ultrasingular" etc. apply to the set $\cup x$, not $x$. After all, $\aleph_\omega$ is singular, because it is the union of $x=\{\aleph_0,\aleph_1,\aleph_2,\ldots\}$, but we don't say that that set is singular. A cardinal is singular, when it is the size of a set that is the union of a small number of small sets.
Nov 5 at 22:31 history edited Zuhair Al-Johar CC BY-SA 4.0
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Nov 5 at 17:53 answer added Joel David Hamkins timeline score: 10
Nov 5 at 17:46 history edited LSpice CC BY-SA 4.0
Typo
Nov 5 at 17:42 history asked Zuhair Al-Johar CC BY-SA 4.0