3 papers
math.AG2022
RDP del Pezzo surfaces with global vector fields in odd characteristic
Gebhard Martin, Claudia Stadlmayr
We classify RDP del Pezzo surfaces with global vector fields over arbitrary algebraically closed fields of characteristic . In characteristic , every RDP del Pezzo sur…
math.AG2021
Automorphism groups of rational elliptic and quasi-elliptic surfaces in all characteristics
Igor Dolgachev, Gebhard Martin
We study the groups of automorphisms of rational algebraic surfaces that admit a relatively minimal pencil of curves of arithmetic genus one over an algebraically closed field of a…
math.AG2019
Automorphisms of unnodal Enriques surfaces
Gebhard Martin
It follows from an observation of A. Coble in 1919 that the automorphism group of an unnodal Enriques surface contains the -congruence subgroup of the Weyl group of the …