Forward, backward and elliptic Harnack inequalities for non-negative solutions to certain singular parabolic partial differential equations. (English) Zbl 1206.35053

DiBenedetto, Emmanuele; Gianazza, Ugo; Vespri, Vincenzo

Ann. Sc. Norm. Super. Pisa, Cl. Sci. (5) 9, No. 2, 385-422 (2010).

The paper deals with the Harnack inequality for non negative solutions of a class of singular, quasilinear, parabolic equations are established. The prototype example is
\[ u_t- \text{div} |Du|^{p-1} Du=0, \quad 1<p<2. \]
The authors prove that non-negative weak solutions satisfy an intrisic form of Harnack inequality provided that \(p_*=\frac{2N}{N+1}<p<2\), which is the optimal range for this estimate.
The relevant fact is that the inequality obtained is a forward and backward in time Harnack estimate as well as a Harnack elliptic type.

Reviewer: Elvira Mascolo (Firenze)

MSC:

35B45	A priori estimates in context of PDEs
35K65	Degenerate parabolic equations
35B65	Smoothness and regularity of solutions to PDEs
35K59	Quasilinear parabolic equations

Keywords:

weak solutions