Classical Yang-Baxter equation from beta-supergravity

Yang-Baxter deformations of superstring sigma-models have recently inspired a supergravity solution generating technique. Using the open/closed string map and a Killing bi-vector as a deformation parameter, new solutions can be built, such that the (generalised) supergravity field equations were conjectured to always reduce to the classical Yang-Baxter equation (CYBE). In this work we provide a proof of this conjecture, using a systematic approach based on the so-called $\beta$-supergravity, which is a dynamical theory for the field ${\beta }^{mn}$ instead of the NSNS 2-form $b_{mn}$.