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Jun 11, 2014 at 8:25 comment added Willie Wong @ChristianClason: those are some nice references. Thanks!
Jun 6, 2014 at 11:33 comment added user51604 Great answers guess is a good idea to follow the literature provided :), yea i was wondering if the Carleman estimates effectively bound the inner norm with some boundary estimates. The jump situation would be really helpful, though i thing the really main problem is somehow how "diagonal" are the operators, which as far as i seen not only matters for the eigenvalue technique but also for the carleman estimate approach (ams.org/journals/tran/2010-362-01/S0002-9947-09-04799-0 Koch and Colombini)
Jun 6, 2014 at 9:31 comment added Christian Clason Regarding Carleman estimates for coupled systems: This seems to be the main current direction for people working on Carleman estimates, especially in the inverse problem and controllability communities; you might want to look there for ideas (see, e.g., Masahiro Yamamoto's survey paper (Section 7.8) or this paper by Jean-Pierre Raymond).
Jun 6, 2014 at 9:20 comment added Christian Clason ...and especially at Nicolas Lerner's lecture notes mentioned in a comment there; Chapter 2 deals with elliptic operators with jumps in the principal coefficient.
Jun 6, 2014 at 7:49 comment added Willie Wong You may want to look at this thread, which may tell you whether you will find the estimates useful. Two other side notes: most versions of Carleman estimates I am aware of requires the operator to have smooth coefficients, and off the top of my head I am not 100% sure whether you have a chance with discontinuous coefficients to even use those inequalities. Also, it is notoriously difficult to get Carleman estimates for coupled systems: most proofs I have seen only apply to (effectively) scalar equations.
Jun 6, 2014 at 7:43 comment added Willie Wong Okay, I see better now what you are doing. The equation that I just tagged as (**) is in the general shape of a Carleman estimate: it controls the $L^p$ norm of some interior quantity with the $L^p$ norm of some boundary quantity. The main difference is that usually Carleman estimates comes with weights (sometimes blowing up at the boundary). So you will have to modify the argument a little bit to control the weights.
Jun 6, 2014 at 7:39 history edited Willie Wong CC BY-SA 3.0
tagged a couple equations so we can refer to them.
Jun 5, 2014 at 16:10 comment added user51604 I updated the thread :)
Jun 5, 2014 at 16:09 history edited user51604 CC BY-SA 3.0
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Jun 5, 2014 at 10:29 history edited user51604 CC BY-SA 3.0
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Jun 5, 2014 at 10:25 comment added user51604 Totally right, sorry for the typos and omissions (first post). It should make sense now, and yes I forgot to mention we deal with critical points, i.e. solutions to a particular divergence form elliptic equation. About the technique I will post it later, as it requires a little bit of space and im short of time :)
Jun 5, 2014 at 10:22 history edited user51604 CC BY-SA 3.0
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Jun 4, 2014 at 11:52 comment added Willie Wong Also, do you mean $e(\nabla u)$ instead of $\nabla e(u)$? The latter doesn't make sense as $u$ is a vector and $e$ acts on square matrices. Are you also assuming that your $u$ solves some sort of an equation? Or perhaps $A$ has certain ellipticity? For arbitrary $u$ I cannot see any estimates being possible for $f(r)$, even in the scalar case. And in the elliptic case then the monotonicity is trivially true for $\alpha \leq 0$, so perhaps you have a certain rate in mind for your $\alpha$?
Jun 4, 2014 at 11:49 comment added Willie Wong Can you indicate some sources for the "several techniques" that one can apply in the scalar case? (I just want to see if an example will jog my memory a bit.)
Jun 4, 2014 at 11:49 history edited Willie Wong
edited tags
Jun 4, 2014 at 11:12 review First posts
Jun 4, 2014 at 11:14
Jun 4, 2014 at 10:56 history asked user51604 CC BY-SA 3.0