Skip to main content
5 events
when toggle format what by license comment
Jun 21, 2016 at 18:30 comment added Pedro Lauridsen Ribeiro I did that, he deals with the homogeneous Cauchy problem only (i.e. without sources). The point is that the loss of derivatives is not that severe for the fixed-point iteration scheme aiming at solving the homogeneous Cauchy problem to work, that's why choosing appropriate norms and interpolating with Gagliardo-Nirenberg saves the day.
Jun 21, 2016 at 10:24 comment added Deane Yang Pedro, I suggest consulting the papers of Klainerman written after the one I cited. The point is that you can use the energy estimates, the Gagliardo-Nirenberg inequalities, and the "right" functional norms (which distinguish the time coordinate from the space coordinates), to get the estimates needed for the Banach space implicit function theorem.
Jun 20, 2016 at 13:29 comment added Pedro Lauridsen Ribeiro Well Deane, if a (say) quasilinear hyperbolic PDE has a source term on the right hand side $$P(\phi)=g(\phi,\partial\phi)\partial^2\phi+H(\phi,\partial\phi)=f\ ,$$ I don't see any obvious way of avoiding using Nash-Moser and solving it with a contraction mapping argument, and that is where you really have to deal with local invertibility - typically, $f$ has the form $f=P(\phi_0)+\tilde{f}$ with $\tilde{f}$ "small". You had to face such a problem in that DMJ paper of yours with Robert Bryant and Phillip Griffiths on low-dimensional isometric embeddings.
Oct 12, 2014 at 17:33 vote accept Tobias Diez
Sep 17, 2014 at 18:51 history answered Deane Yang CC BY-SA 3.0