Mathematics

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Apr 21, 2019 05:33
@Rithaniel You already can't star your own message right? Unless you're a moderator
2
Apr 21, 2019 05:31
@loch Apparently I didn't read this properly at all... Thanks (for some reason I took it to be the max ideal of O_Y,y and it contraction, rather than max ideal of O_X,x and its extension - oh well I better sleep before I make more mistakes)
Apr 21, 2019 05:29
Oh, I just realised there are 4 of them lol
Apr 21, 2019 05:28
Since they self upvoted their question, and they got an answer
Apr 21, 2019 05:28
@LeakyNun Well they got what they wanted I guess
Apr 21, 2019 05:16
Thanks for your help @loch
Apr 21, 2019 05:13
No wonder i'm super confused
Apr 21, 2019 05:13
For some dumb reason, I've just been checking closed points
Apr 21, 2019 05:12
Crap! Good point
Apr 21, 2019 05:11
What more basic definition is there than the exterior measure here??
Apr 21, 2019 05:10
Just noticing the instant starring, and same typing style
Apr 21, 2019 05:10
/ all working on the same homework assignment?
Apr 21, 2019 05:10
Bhowmick, Hansie, RockDock, are you all the same person
Apr 21, 2019 05:07
But your statement about dilation holds in R^d with cubic covers, and the same argument described above
Apr 21, 2019 05:07
By cubic cover, I mean you are computing the exterior measure, where in one dimension, a cubic cover is just a cover by closed intervals
Apr 21, 2019 05:06
And then you can see that the cubic covers have the same volume
Apr 21, 2019 05:05
and showing that multiplying by k^{-1} sends cubic cover to cubic cover
Apr 21, 2019 05:05
@RockDock You can show this by taking a standard cubic cover
Apr 21, 2019 05:03
Why not, with the definition on wiki for unramified en.wikipedia.org/wiki/Glossary_of_algebraic_geometry#U
Apr 21, 2019 05:02
Then that seems satisfied too
Apr 21, 2019 05:02
and giving K\to O_{A^1,x}/m_x as a separable field extension
Apr 21, 2019 05:01
But if I take unramified as locally of finite type, which seems to be satisfied
Apr 21, 2019 05:01
Why is A^1_K not etale over Spec(K)?
Apr 21, 2019 04:59
The unramified contains relative dim 0 somehow
Apr 21, 2019 04:59
How do I see that to be equivalent to smooth and unramified?
Apr 21, 2019 04:58
How the hell have I not seen that definition :'(
Apr 21, 2019 04:58
@loch So $Y$ has to have dimension $0$???
Apr 21, 2019 04:11
I guess I expect there to be lots of other etale morphisms, like many smooth schemes such as $\Bbb A^n_K$, but perhaps someone knows one extra condition that makes the separable field extensions the entire class
Apr 21, 2019 04:08
If $L$ is a finite separable field extension of the field $K$, then $Spec(L)\to Spec(K)$ is etale. Does this actually classify all etale morphisms $Y\to Spec(K)$ to a field? Or are there high dimensional etale covers etc?
Apr 3, 2019 23:31
@user193319 does $\Bbb{Q}(\sqrt{2},\sqrt{3})$ contain $\sqrt{6}$. Does $\Bbb{Q}[\sqrt{2},\sqrt{3}]$?
Apr 3, 2019 23:23
Since cohomology of spaces with Z coefficients is just homology of spaces with torsion shifted up a degree, is it true that rational homology and rational cohomology agree in all degrees
Apr 3, 2019 12:28
Is the topology on the manifold that the regular value gives you the subspace topology?
Apr 3, 2019 02:10
I wonder why this room is becoming less active over time. I guess there are many other places to chat now about mathematics?
Feb 9, 2019 13:58
@Rithaniel Things will be much worse in due time. Your language will undergo highly nontrivial deformations with probability measure 1.
Feb 8, 2019 03:57
What are F and G?
Feb 6, 2019 09:42
Do you mean in reality, or in logic, or what?
Feb 6, 2019 09:42
@Secret What are these different shades of nothingness?
Feb 4, 2019 07:07
?
Feb 4, 2019 07:07
Like you are forbidding saying stuff like $a\in A\cap (B\cup C)$ so $a\in A$ and $a\in (B\cup C)$
Feb 4, 2019 07:06
You don't want to prove it by studying where elements live? @nurunnesha
Feb 4, 2019 06:14
^
Feb 4, 2019 06:07
btw who is -> who'is -> who's
Feb 4, 2019 06:06
eyes here
Feb 4, 2019 05:41
and look at that graphic
Feb 4, 2019 05:40
please consider my responses before writing any more proofs
Feb 4, 2019 05:35
@user330477 https://en.wikipedia.org/wiki/Second_derivative#/media/File:Animated_illustration_of_inflection_point.gif

This graphic might help. When it's blue, the second derivative is positive (green it's negative)
Feb 4, 2019 05:33
It's not right for the three reasons I list above
Feb 4, 2019 05:33
Also, there may be (and are) points that aren't critical between a and b, such that f''>0 and f''<0 (i.e. you have to be careful with using your criterion when f'\ne 0)
Feb 4, 2019 05:27
Also, the function is decreasing for some time, and then it is increasing for some time, does your description of f' agree with this intuition?
Feb 4, 2019 05:25
@user330477 did you get f''>0 with the sign the wrong way, and this carried through everything else?