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Jun 28, 2010 at 20:03 vote accept Kaminoite
Jun 28, 2010 at 19:06 answer added Scott Armstrong timeline score: 1
Jun 28, 2010 at 15:53 comment added Willie Wong books.google.com/… ... this Gilbarg and Trudinger.
Jun 28, 2010 at 15:33 comment added Kaminoite @ Willie Wong: I corrected the typo about the dependence of $C$ on $z$. About the literature, can you tell me exactly which are Gilbarg and Trudinger?
Jun 28, 2010 at 15:31 history edited Kaminoite CC BY-SA 2.5
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Jun 28, 2010 at 14:19 comment added Willie Wong It also looks like you may want to look at the literature for boundary regularity of elliptic equations. See Gilbarg and Trudinger for example.
Jun 28, 2010 at 14:18 comment added Willie Wong Another point: your question is still a bit fishy. The constant $C(s)$ in your last formula MUST depend on $z$. Ideally instead of the limit being equal some $C(s)$, it should be some inequality (presumably less-than-or-equal-to). I think this may be an interesting problem, but as it stands, the phrasing of the question is not clear. I am not even sure what the question is!
Jun 28, 2010 at 13:12 comment added Andrey Rekalo @Kaminoite: Thank you for the comment. I thought $u_s$ was supposed to be harmonic everywhere in $B$.
Jun 28, 2010 at 12:57 comment added Kaminoite @Andrey Rekalo: The condition ${u_s}_{|K}(x) = {u_0}_{|K}(x)+sg(x)$ is not redundant. In fact, you can think that $K$ is part of the boundary for a new $\bar{\Omega} = \Omega-K$.
Jun 28, 2010 at 12:55 comment added Kaminoite The solution must be harmonic in $B-K$ for all $s$.
Jun 28, 2010 at 12:39 comment added Willie Wong @Kaminoite: for the perturbed problem, do you actually want $\triangle u_s = 0$ only on $B\setminus K$? If $u_s$ is not differentiable near $\partial K$ (as indicated by the bit after "MY QUESTION IS"), it can hardly be a harmonic function in $B$. If this is the case, aren't you just looking at the Dirichlet problem on $B\setminus K$ with $u | \partial B = 0$ and $u | \partial K = s g$? Then you are just comparing arbitrary extensions of $g$ into $K$ against harmonic extensions of $g$ into $B\setminus K$...
Jun 28, 2010 at 12:14 comment added Andrey Rekalo I don't understand the question. The condition ${u_s}_{|K}(x) = {u_0}_{|K}(x)+sg(x)$ is redundant since a harmonic function on $B$ is uniquely determined by its trace on $\partial B$.
Jun 28, 2010 at 12:05 history edited Kaminoite CC BY-SA 2.5
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Jun 28, 2010 at 11:09 history asked Kaminoite CC BY-SA 2.5