timur
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 Mar22 comment show $\sum_{i=1}^Nx_i\bar{y_i}$ is defined Square summability would be enough, which is weaker than absolute convergence. Mar21 awarded Necromancer Mar17 awarded Enlightened Mar17 awarded Nice Answer Feb11 comment oblique derivative smoothness of harmonic functions @Andrew: I overlooked the condition $f\in C(S)$, but I am pretty sure your statement is true. I take back the smoothness statement though. I am not sure what you mean by "which assume that solutions are from ..." but the Schauder estimates you mention imply additional regularity, given that the solution has some minimal regularity to start with. Feb11 answered oblique derivative smoothness of harmonic functions Feb1 revised Convergence of a crazy power series added 3 characters in body Feb1 answered Convergence of a crazy power series Feb1 comment A power series problem, find ROC $|\sin x|\leq|x|$ is a good bound when $x$ is small, but for large $x$ one should use $|\sin x|\leq1$. Jan31 answered Radius of convergence powers series s.t seriex $\sum |a_n|$diverges Jan21 awarded Nice Answer Dec16 awarded Caucus Dec15 revised Method of characteristics for systems of PDE (vs. Lewy's example) added 112 characters in body Dec15 answered Method of characteristics for systems of PDE (vs. Lewy's example) Dec14 comment Sobolev space is an algebra @MathematicalPhysicist: Write $\|\hat u\|_{L^1}=\int<\xi>^{-s}<\xi>^{s}|\hat u(\xi)|\mathrm{d}\xi$, and apply Cauchy-Schwarz. The condition $2s>n$ gives integrability of $<\xi>^{-2s}$. Dec14 comment For which $s\in\mathbb R$, is $H^s(\mathbb T)$ a Banach algebra? possible duplicate of Sobolev space is an algebra Nov28 comment Is this bootstrap argument correct? @BeniBogosel: For $\phi$ an arbitrary smooth function on the boundary, we have $\int_{\partial\Omega}v_n\phi=0$. By weak convergence, $\int_{\partial\Omega}w\phi=0$. Since $\phi$ is arbitrary, $w=0$ on $\partial\Omega$. Nov21 comment Non-ellipticity of Yang-Mills equations Do you consider accepting my answer? Nov14 comment Dual space of Bochner space I was wondering if one can derive the general case from the case where $H=\mathbb{R}^n$ by some approximation argument. I think this would be more accessible pedagogically since it would rely on the familiar scalar case. Nov1 comment Use $C^\infty$ function to approximate $W^{1,\infty}$ function in finite domain (6) and (7) follow from triangle inequalities applied to your claim, no?