{ "id": "1104.0306", "version": "v1", "published": "2011-04-02T09:16:17.000Z", "updated": "2011-04-02T09:16:17.000Z", "title": "A general fractional porous medium equation", "authors": [ "Arturo de Pablo", "Fernando Quirós", "Ana Rodríguez", "Juan Luis Vázquez" ], "comment": "43 pages, 2 figures", "categories": [ "math.AP" ], "abstract": "We develop a theory of existence and uniqueness for the following porous medium equation with fractional diffusion, $$ \\{ll} \\dfrac{\\partial u}{\\partial t} + (-\\Delta)^{\\sigma/2} (|u|^{m-1}u)=0, & \\qquad x\\in\\mathbb{R}^N,\\; t>0, [8pt] u(x,0) = f(x), & \\qquad x\\in\\mathbb{R}^N.%. $$ We consider data $f\\in L^1(\\mathbb{R}^N)$ and all exponents $0<\\sigma<2$ and $m>0$. Existence and uniqueness of a weak solution is established for $m> m_*=(N-\\sigma)_+ /N$, giving rise to an $L^1$-contraction semigroup. In addition, we obtain the main qualitative properties of these solutions. In the lower range $0