Inseparable maps on $W_n$valued Ext groups of nontaut rational double point singularities and the height of K3 surfaces
Abstract
We give lower bounds of, or moreover determine, the height of K3 surfaces in characteristic $p$ admitting nontaut rational double point singularities or actions of local group schemes of order $p$ ($\mu_p$ or $\alpha_p$). The proof is based on the computation of the pullback maps by inseparable morphisms, such as Frobenius, on certain $W_n$valued Ext groups of rational double points.
 Publication:

arXiv eprints
 Pub Date:
 July 2019
 arXiv:
 arXiv:1907.04686
 Bibcode:
 2019arXiv190704686M
 Keywords:

 Mathematics  Algebraic Geometry;
 14J28 (Primary) 14L20;
 14J17;
 14B15 (Secondary)
 EPrint:
 30 pages, comments welcome