Bessel Inequality and the Basis Property for a $$2m\times 2m $$ Dirac Type System with an Integrable Potential

Abstract

We study the Bessel and basis properties of root vector functions of a Dirac type operator with an integrable potential. Criteria for the Bessel and basis properties are established, and a theorem on the equivalent basis property in $$L_{2}^{2m}(0,2\pi )$$ is proved.