Proper homothetic vector fields in Bianchi type-I space-time.
Pseudo-Riemannian and Hessian geometry related to Monge-Ampère structures
We study properties of pseudo-Riemannian metrics corresponding to Monge-Ampère structures on four dimensional . We describe a family of Ricci flat solutions, which are parametrized by six coefficients satisfying the Plücker embedding equation. We also focus on pullbacks of the pseudo-metrics on two dimensional , and describe the corresponding Hessian structures.