Published online by Cambridge University Press: 14 November 2011
A characterisation is obtained of all the regularly solvable operators and their adjoints generated by general ordinary quasidifferential expressions in The domains of these operators are described in terms of boundary conditions involving the solutions of M[u] = λwu and the adjoint equation at both singular end-points a and b. These results are an extension of those proved in [3], by Evans and Ibrahim, to the case of two singular end-points of the interval (a, b), and a generalisation of those in [10] and [13] concerning selfadjoint and J-selfadjoint differential operators, where J denotes complex conjugation.