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Timeline for Definition of a spin group

Current License: CC BY-SA 4.0

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Oct 28, 2023 at 20:00 comment added LSpice @Kevin, re, but, as @‍Eric points out, the set of products of elements of the empty set is the singleton set containing the identity (because $\prod_{x \in \emptyset} x = 1$, which I was sure was an answer to Interesting examples of vacuous / void entities but doesn't seem to be), not the empty set.
Oct 28, 2023 at 18:47 answer added S. Carnahan timeline score: 5
Aug 5, 2022 at 13:15 history edited Eric CC BY-SA 4.0
Revert incorrect edit
Aug 5, 2022 at 10:58 history edited YCor CC BY-SA 4.0
formatting, added tag
Aug 4, 2022 at 17:22 comment added Kevin There aren't any elements with norm 1, so as is literally written $Pin(V)$ is empty. If you assume it at least contains 1, you get the trivial group. That's silly!
Aug 4, 2022 at 16:59 history edited Eric CC BY-SA 4.0
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Aug 4, 2022 at 16:58 comment added Eric I don't follow; why do the later definitions preclude a group structure? I assume the empty product ($1$) of no elements of $V$ is still considered an element of the spin group.
Aug 4, 2022 at 15:50 comment added Kevin Strange, it seems like the latter definitions must be assuming positive definiteness. Otherwise it doesn't even define a group (no identity), let alone a double cover of $SO$!
Aug 4, 2022 at 15:40 history edited Eric CC BY-SA 4.0
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S Aug 4, 2022 at 13:20 review First questions
Aug 4, 2022 at 13:24
S Aug 4, 2022 at 13:20 history asked Eric CC BY-SA 4.0