most recent 30 from http://mathoverflow.net 2013-05-20T06:46:23Z http://mathoverflow.net/feeds/user/30985 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/120137/how-to-define-laplacian-on-l-2 John Zheng 2013-01-28T18:35:08Z 2013-01-29T08:16:06Z

<p>This might be a dumb question, but I thought the Laplacian (classical) is defined for $C^2$ functions. How do we extend that to be a self-adjoint operator on all of $L_2$? Is it the so called Friedrich's extension theorem? Is the extension explicit? How would I, for example, compute the Laplacian of |x|</p> <p>Thanks</p>