On the spectra of non-selfadjoint differential operators and their adjoints in direct sum spaces

摘要

The general ordinary quasidifferential expressionMpofnthorder, with complex coefficients and its formal adjointMp+on any finite number of intervalsIp=(ap,bp),p=1,…,N, are considered in the setting of the direct sums ofLwp2(ap,bp)-spaces of functions defined on each of the separate intervals. And a number of results concerning the location of the point spectra and regularity fields of general differential operators generated by such expressions are obtained.