Baer, Rickart, and Quasi-Baer Rings

Abstract

This chapter is devoted to properties of rings for which certain annihilators are direct summands. Such classes of rings include those of Baer rings, right Rickart rings, quasi-Baer rings, and right p.q.-Baer rings. The results and the material presented in this chapter will be instrumental in developing the subject of our study in later chapters. It is shown that the Baer and the Rickart properties of rings do not transfer to the rings of matrices or to the polynomial ring extensions, while the quasi-Baer and the p.q.-Baer properties of rings do so. The notions of Baer and Rickart rings are compared and contrasted in Sect. 3.1 and the notions of quasi-Baer and principally quasi-Baer rings in Sect. 3.2, respectively. A result of Chatters and Khuri shows that there are strong bonds between the extending and the Baer properties of rings. We shall also see some instances where the two notions coincide. It is shown that there are close connections between the FI-extending and the quasi-Baer properties for rings.