TY  - JOUR
AU  - Xiang, Yanyu
AU  - Wang, Aiping
PY  - 2023
TI  - On symmetry of the product of two higher-order quasi-differential operators
JO  - AIMS Mathematics
SP  - 9483
EP  - 9505
VL  - 8
IS  - 4
AB  - The symmetric realizations of the product of two higher-order quasi-differential expressions in Hilbert space are investigated. By means of the construction theory of symmetric operators, we characterize symmetric domains determined by two-point boundary conditions for product of two symmetric differential expressions with regular or limit-circle singular endpoints. The presented result contains the characterization of self-adjoint domains as a special case. Several examples of singular symmetric product operators are given.
UR  - https://doi.org/10.3934/math.2023478
DO  - 10.3934/math.2023478