Semi-local ring


In mathematics, a semi-local ring is a ring for which R/J is a semisimple ring, where J is the Jacobson radical of R.
The above definition is satisfied if R has a finite number of maximal right ideals. When R is a commutative ring, the converse implication is also true, and so the definition of semi-local for commutative rings is often taken to be "having finitely many maximal ideals".
Some literature refers to a commutative semi-local ring in general as a
quasi-semi-local ring, using semi-local ring to refer to a Noetherian ring with finitely many maximal ideals.
A semi-local ring is thus more general than a local ring, which has only one maximal ideal.

Examples