The Stacks project

Definition 90.3.2. Let $f: B \to A$ be a ring map in $\mathcal{C}_\Lambda $. We say $f$ is a small extension if it is surjective and $\mathop{\mathrm{Ker}}(f)$ is a nonzero principal ideal which is annihilated by $\mathfrak {m}_ B$.

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