# Publishing house / Banach Center Publications / All volumes

## Banach Center Publications

PDF files of articles are only available for institutions which have paid for the online version upon signing an Institutional User License.

## Elliptic operators in the bundle of symmetric tensors

### Volume 113 / 2017

Banach Center Publications 113 (2017), 193-218 MSC: Primary: 58J32, 53C15, 53C21; Secondary: 58G05, 53C21, 58C40. DOI: 10.4064/bc113-0-11

#### Abstract

Differential operators: the gradient $\operatorname{grad}$ and the divergence $\operatorname{div}$ are defined and examined in the bundles of symmetric tensors on a Riemannian manifold. For the second order operator $\operatorname{div} \operatorname{grad}$ which appears to be elliptic and a manifold with boundary a system of natural boundary conditions is constructed and investigated. There are $2^{k+1}$ conditions in the bundle $S^k$ of symmetric tensors of degree $k$. This is in contrast to the bundle of skew-symmetric forms where (for analogous differential operators) there are always four such conditions independently of the degree of forms (i.e. independently of $k$). All the $2^{k+1}$ conditions are investigated in detail. In particular, it is proved that each of them is self-adjoint and elliptic. Such ellipticity of a given boundary condition has an essential significance for the existing of a discrete spectrum and an orthonormal basis in $L^2$ consisting of smooth sections that are the eigenvectors of the operator and satisfy the boundary condition. Some special cases, e.g. $k=1$ or the cases that the boundary is umbilical or totally geodesic, are also discussed.

#### Authors

• Anna KimaczyńskaFaculty of Mathematics and Computer Science
University of Łódź
Banacha 22
90-238 Łódź, Poland
e-mail
• Antoni PierzchalskiFaculty of Mathematics and Computer Science
University of Łódź
Banacha 22
90-238 Łódź, Poland
e-mail

## Search for IMPAN publications

Query phrase too short. Type at least 4 characters.