A priori bounds for semielliptic operators

We derive L-p a priori bounds for semielliptic operators, with variable mat rix coefficients, in domains in R-n. The results are applicable to elliptic , parabolic, and p-parabolic operators. as well as to more general operator s. We direct special attention to the nature of the dependence of constants involved in these bounds upon coefficient bounds and semiellipticity const ants. (C) 2001 Academic Press.