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8:00 AM
A new tag was created by Emptymind.
Q: Understanding steps in a proof.

EmptymindA part of the proof is given below: My questions are: 1- I do not understand why "Since $f'(x) = 0$, we can find $y_{x} > o$ such that we have both $[x,y_{x}] \subseteq (a,b)$ " could anyone explain this step for me please? 2- Why the set $\mathcal{B}$ is a vitali cover of $E$? where is ...

In mathematics, the Vitali covering lemma is a combinatorial and geometric result commonly used in measure theory of Euclidean spaces. This lemma is an intermediate step, of independent interest, in the proof of the Vitali covering theorem. The covering theorem is credited to the Italian mathematician Giuseppe Vitali. The theorem states that it is possible to cover, up to a Lebesgue-negligible set, a given subset E  of Rd by a disjoint family extracted from a Vitali covering of E. == Vitali covering lemma == === Statement of the lemma === Finite version: Let B...
14 hours later…
10:16 PM
I've posted an answer in the 2019 tag management thread to solicit comments about my proposal to add a tag: math.meta.stackexchange.com/a/30915/155629
10:33 PM
A: Tag management 2019

Travis WillseProposal: Add the tag gradient. This tag is intended for questions about or involving the gradient operator, which is a major theme in vector calculus and also important differential geometry. Probably most questions using this tag would also be tagged with vector-analysis or vector-calculus, bu...

11:17 PM
Thanks for making the post on meta! We'll see how people vote on that (and whether there is some useful feedback in the comments).

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