A subset of a ring is called nil if each element of it is nilpotent (cf. Nilpotent element). An ideal of is a nil ideal if it is a nil subset. There is a largest nil ideal, which is called the nil radical. One has that
where denotes the Jacobson radical of and is the prime radical of , i.e. the intersection of all prime ideals of . Each of the inclusions can be proper. If is commutative, . The prime radical is also called the lower nil radical, and the nil radical the upper nil radical.
|[a1]||C. Faith, "Algebra" , II. Ring theory , Springer (1976)|
|[a2]||J.C. McConnell, J.C. Robson, "Noncommutative Noetherian rings" , Wiley (1987)|
|[a3]||L.H. Rowen, "Ring theory" , 1 , Acad. Press (1988)|
Nil ideal. Encyclopedia of Mathematics. URL: http://www.encyclopediaofmath.org/index.php?title=Nil_ideal&oldid=12426