Title: Porous media: the Muskat and Hele-Shaw problems.

Abstract: 
The Muskat problem involves filtration of two incompressible fluids  
throughout a porous medium. In this seminar we shall discuss  in 3-D  
the relevance of the Rayleigh-Taylor condition, and the topology of  
the initial interface, in order to obtain local existence in Sobolev  
spaces.