Gyu Eun Lee
Reputation
9,497
Top tag
Next privilege 10,000 Rep.
Access moderator tools
 Oct 17 answered Why does the De Moivre formula work? Oct 13 comment Additivity of Outer Measure for Separated Bounded Sets (using definition of an outer measure only) In one dimension, open balls are disjoint unions of at most countably many intervals. Oct 13 comment Additivity of Outer Measure for Separated Bounded Sets (using definition of an outer measure only) While I suggest you write it up more carefully than as it is right now, the ideas for your part 1 are generally sound. Oct 12 answered Additivity of Outer Measure for Separated Bounded Sets (using definition of an outer measure only) Oct 11 comment Extension theorem Sobolev spaces @JohnSmith Ah, yes, you're absolutely right. Oct 11 comment Extension theorem Sobolev spaces This proposition is proved for $1\leq p\leq \infty$ in section 5.4 of L. Evans, *Partial Differential Equations.*Rather than mollifying, the idea in this reference is to use the local flatness of the boundary to reflect the function $u$ across it, and define the extension via this reflection. He also remarks that the proof gives an extension for $W^{2,p}$ as well, provided the boundary is $C^2$. Oct 10 reviewed Approve How do I find the derivative of $\frac{1}{2\sqrt{x}}$ using the definition of the derivative? Oct 10 reviewed Approve Difficulty in understanding the steps of given proof. Oct 10 reviewed Close Second Order ODE with an additional Constant Oct 10 reviewed Close finding the limit as n goes to infinity Oct 10 reviewed Close Is there a series that converges for finitely many terms but not convergent as limit goes to infinity? Oct 10 reviewed Close $6 \Bbb Z + 5$ contains infinitely many primes Oct 10 reviewed Leave Open How to solve this absolute value inequality? $|x| + |x - 2| \gt 5$ Oct 10 reviewed Leave Open How to obtain the negative rational numbers Oct 10 reviewed Close The calculation of a series Oct 10 reviewed Close Expression for gcd( ( 0! x n! ) , ( 1! x n-1!) , ( 2! x n-2! ) ,…(k!,n-k!) ) Oct 10 reviewed Close Prove that the set $\mathbb R\times\mathbb R$ is equipotent to the set $\mathbb R$? Oct 10 reviewed Close How to determine if a point falls on a vector given 2 points and a unit vector. Oct 10 reviewed Close Inequalities involving the existence of a constant factor Oct 10 reviewed Leave Open Probability of wearing a hat