الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
A ring R is called a right PP-ring if every principal right ideal is projective, equivalently if the right annihilator r(a) is generated by anidempotent for every element a of R. These rings seem first to have been discussedby A. Hattori 1 in 1960.Butin1958, S. Maeda 2 had defined before Rickart rings to be the rings in which the right and left annihilators of every element are generated byidempotents. By the same way he defined Rickart rings. A Rickart-ring is a -ring whose the right annihilator of every element a of R is generated by aprojection. The term ”Rickartring” was introduced in honor of C.E. Rickart 3, who studied the corresponding property in rings of operators. Obviously, the analogous property for right annihilators is automatically fulfilled inthiscase.