Degenerate and singular parabolic equations have been the subject of
extensive research for the last 25 years. Despite important
achievements, the issue of the Harnack inequality for non-negative
solutions to these equations, both of p-Laplacian and porous medium
type, while raised by several authors, has remained basically open.
Recently considerable progress has been made on this issue, to the point
that, except for the singular sub-critical range, both for the
p-laplacian and the porous medium equations, the theory is reasonably
complete.
It seemed therefore timely to trace a comprehensive overview, that would
highlight the main issues and also the problems that still remain open.
The authors give a comprehensive treatment of the Harnack inequality for
non-negative solutions to p-laplace and porous medium type equations,
both in the degenerate (p>2 or m>1) and in the singular range
(1pmThe book is self-contained. Building on a similar monograph by the
first author, the authors of the present book focus entirely on the
Harnack estimates and on their applications: indeed a number of known
regularity results are given a new proof, based on the Harnack
inequality. It is addressed to all professionals active in the field,
and also to advanced graduate students, interested in understanding the
main issues of this fascinating research field.