Modules And Dimensions Over Formal Triangular Matrix Rings

In this paper,it is mainly studied the modules and their dimensions over formal triangular matrix rings of order 2 and n are studied.First of all,it is characterized PGF modules and their dimensions over formal triangular matrix rings of order 2.Secondly,a condition for the module being Ding projective over formal triangular matrix ring of order n is obtained,and another condition for the module being PGF over formal triangular matrix ring of order n is obtained.Finally,the dimensions of Ding projective modules over formal triangular matrix ring of order n are characterized.