Herzog's conormal module conjecture

Let $R$ be a Noetherian ring and $I\subset R$ be an ideal. The conormal module is $I/I^2$, regarded as an $R/I$-module.

Herzog's conormal module conjecture. If $I/I^2$ has finite projective dimension as an $R/I$-module, then $I$ is a complete intersection.

This conjecture concerns a homological criterion for an ideal to be a complete intersection. Although it is presented as a conjecture in the introduction, the paper states that Benjamin Briggs resolved it in full generality; its database status is therefore solved.