摘要 : We study conformal deformation problems on manifolds with boundary which include prescribing sigma(k )(math) 0 in the interior. In particular, we prove a Dirichlet principle when the induced metric on the boundary is fixed and an ... 展开 We study conformal deformation problems on manifolds with boundary which include prescribing sigma(k )(math) 0 in the interior. In particular, we prove a Dirichlet principle when the induced metric on the boundary is fixed and an Obata-type theorem on the upper hemisphere. We introduce some conformally covariant multilinear operators as a key technical tool. (C) 2018 Elsevier Inc. All rights reserved. 收起