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All rings are supposed to have a unit element $1$ here. Let $N\subset \mathbb N_{\geqslant 2}$ be the set such that $n\in N$ if, and only if, there does not exist a non commutative ring of cardinal $n$. For instance, $16\notin N$ because $A=M_2(\mathbb F_2)$ is a non commutative ring and $\ver... 0 Guys I have this problem: Is it true that the tautological bundle on$\mathbb{P}^1(\mathbb{C})$given by$L(-1)=\lbrace (\ell,z)\in\mathbb{P}^1\times \mathbb{C}^2 \: : \: z\in \ell \rbrace $is a subbundle of$L(0)^2$, where$L(0)\cong \mathbb{P}^1\times \mathbb{C}$? The tag creator also created tag-excerpt for line-bundles. 1 hour later… 7:46 AM Only now I noticed that tag also has tag-excerpt. I am in favor of getting rid of this tag. Looks like a case of useless badge-hunting to me. — Jyrki Lahtonen ♦ 35 mins ago @JyrkiLahtonen I guess score +4 is sufficient to consider it a consensus. (We do not get a lot of votes on tag-related issues.) Will the tag be removed by mods (assuming you and other mods agree that it should be removed), or should it be removed manually? — Martin Sleziak 15 mins ago @MartinSleziak I started removing it manually, but if I figure out /recall how to remove it with a single strike I will :-) — Jyrki Lahtonen ♦ 5 mins ago Currently has 67 question. @JyrkiLahtonen I can only write what I recall other mods mentioned. It seems that merging two tags effectively removes the tag. But this is probably not an ideal option here. So I guess there's no way to do this without involving a dev. (Well, other than merging, which is no good here.) Perhaps some more experienced user knows more about this? @JyrkiLahtonen I guess that other than merging with another tag - which is probably not good for this tag - mods probably can't do it. Anyway, since this is unrelated to this specific tag, we can move the discussion to chat. (Although I am not sure there is much to be added.) — Martin Sleziak 5 secs ago Anyway, I will start with the ones which are not tagged geometry. Just in case that merging could be a reasonable solution at least for some of them. (If all remaining questions with this tag are also tagged geometry, maybe they can be retagged without boumping..) Re: case of useless badge-hunting. Seeing that several from the most active editors have been temporarily suspended, I should probably be more careful with my edits, too. 2 hours later… 10:26 AM Would there be some suitable tags to add to this question. What about ? And ? 2 I was reading an article about back ground of Killing's work by Thomas Hawkins from Historia mathematica$1980\$ (doi: 10.1016/0315-0860(80)90027-0). It was written that Killing stated that if one drop assumptions infinitude of straight line and parallel postulates four possibilities arise, which ...

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@MartinSleziak I have added tag-wiki - I admit that it contains almost nothing, but in the tag-wiki I have at least possibility to add Wikipedia link - links are not possible in tag-excerpt.