Jacobson radical

Let \(R\) be a commutative ring. The Jacobson radical of \(R\) is the intersection of all maximal ideals of \(R\): \[ \jacobsonrad{R} \coloneqq \Intersect_{\mfm \in \mspec R} \mfm, \] where \(\mspec R\) is the max spectrum of \(R\).