On the Lp-theory of CO-semigroups associated with second-order elliptic operators, I

We study L-p-theory of second-order elliptic divergence-type operators with measurable coefficients To this end. we introduce a new method of constructing. positive C-0-semigroups on L-p associated with sesquilinear (not necessarily sectorial) forms in L, A precise condition ensuring that the elliptic operator is associated with a quasi-contractive C-0-semigroup on L-p is established (C) 2002 Elsevier Science (USA).