Biregular models of log Del Pezzo surfaces with rigid singularities

Abstract:

We construct biregular models of families of log Del Pezzo surfaces with rigid cyclic quotient singularities such that a general member in each family is wellformed and quasismooth. Each biregular model consists of infinite series of such families of surfaces; parameterized by the natural numbers $\mathbb {N}$. Each family in these biregular models is represented by either a codimension 3 Pfaffian format modelled on the Plücker embedding of $\mathrm {Gr}(2,5)$ or a codimension 4 format modelled on the Segre embedding of $\mathbb {P}^2 \times \mathbb {P}^2$. In particular, we show the existence of two biregular models in codimension 4 which are biparameterized, giving rise to an infinite series of models of families of log Del Pezzo surfaces. We identify those biregular models of surfaces which do not admit a $\mathbb {Q}$-Gorenstein deformation to a toric variety.