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 Nov 21 asked Why is the union of two closed sets again closed in the Scott topology? Nov 19 comment At what point is the phrase “couldn't go slower” true. It’s another thing if you’re actually asking about the slowest possible speed using a car. Then you would probably have to specify the car, including engine, gears and whatnot, the road, including slope, ground, the possibly weather. I dunno. But you most certainly would have to ask a physicist or an engineer or maybe both, but not a mathematician. Nov 19 comment At what point is the phrase “couldn't go slower” true. This is rather a physics question. If you talk about idealised motion, then you can always go a little slower without stopping. Take your favorite unit of measurement for speed. Take your favorite candidate for “the slowest speed” (such that you can’t go slower without stopping). Measure that speed. Take half of what you got. Move that fast. There you go, a little bit slower than before. Nov 17 answered Prove that a Linear-Map is surjective. Nov 17 comment Prove that a Linear-Map is surjective. Write “Let $V = \{p ∈ ℝ[X];~\deg p ≤ 2\}$” in the beginning and change $g$’s signature to “$V → ℝ^3$”. (You mean “less or equal to”, by the way.) Nov 17 comment Prove that a Linear-Map is surjective. What is $R2[X]$? Did you mean to write $ℝ[X]$? Nov 17 comment Is the following union connected Are $U_ω;~ω ∈ J$ open sets? Nov 10 comment Holomorphic in a unit disk based on Identity Theorem If $f_1\lvert_D = f_2\lvert_D$ and $1/2 ∈ D$, … Nov 10 comment Is there a name for a monoid with a distinguished absorbing element? I think I might just call it “steroid” … Nov 9 comment Is there some sort of trick to show naturality? @QiaochuYuan Ok, well. It’s good that you can see it, but it’s a shame you can’t describe what’s going on. If you ever find a good phrase or some sort of intuition you can convey, I would be extremely interested! It might also help for the likes of me if you could pinpoint to what sort of experience enabled you to see naturality (if there was one). (Thanks in any case.) Nov 9 comment Is there a name for a monoid with a distinguished absorbing element? @rschwieb Yes, exactly. A little background for this question: Valuations on fields $F$ are morphisms $F → M$ of such structures (with an additional requirement of some subaddivity of “$+$” and “$∨$”), where $M$ is an ordered group with an adjoint absorbing element at the bottom. Then, $M^×$ would be called the valuation group. Nov 9 comment Is there some sort of trick to show naturality? @QiaochuYuan Is this a joke? Seriously, I can’t tell. Nov 9 asked Is there some sort of trick to show naturality? Nov 8 comment Use of the symbol $\lneq$ Is it? Or is it just not deemphasizing that it is not not inequal? Nov 8 comment Use of the symbol $\lneq$ Though I agree with you, not everyone thinks of “$\subset$” and “$\subsetneq$” as different relations. Nov 7 revised Group actions and quotient groups deleted 1 character in body Nov 7 revised Group actions and quotient groups added 65 characters in body Nov 7 answered Group actions and quotient groups Nov 7 revised Is there a name for a monoid with a distinguished absorbing element? deleted 181 characters in body Nov 7 asked Is there a name for a monoid with a distinguished absorbing element?