Study of formal triangular matrix rings

In this paper we carry out a systematic study of various ring theoretic pro perties of formal triangular matrix rings. Some definitive results are obta ined on these rings concerning properties such as being respectively left K asch, right mininjective, clean, potent, right PF or a ring of stable rank less than or equal to n. The concepts of a strong left Kasch ring, a strong right mininjective ring are introduced and it is determined when the trian gular matrix rings are respectively strong left Kasch or strong right minin jective. It is also proved that being strong left Kasch or strong right min injective are Morita invariant properties.