Jacobson radical

Let \(A\) be a ring Then the jacobson radical \(\mathcal{J}_A\) is defined as intersection of (left-)maximal ideals

\begin{align*} \mathcal{J}_A = \bigcap_{\mathfrak{m} \in \mathrm{Spec}_{\mathrm{max}}(A)} \mathfrak{m} \end{align*}

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