Abstract:
We introduce and study the notion of $G$-coregularity of algebraic varieties endowed with an action of a finite group $G$. We compute the $G$-coregularity of smooth del Pezzo surfaces of degree at least $6$, and give a characterization of groups that can act on conic bundles with $G$-coregularity $0$. We describe the relations between the notions of $G$-coregularity, $G$-log canonical thresholds, $G$-birational rigidity, and exceptional quotient singularities.
Citation:
K. V. Loginov, V. V. Przyjalkowski, A. S. Trepalin, “$G$-Coregularity of del Pezzo Surfaces”, Birational Geometry and Fano Varieties, Collected papers. Dedicated to Yuri Gennadievich Prokhorov on the occasion of his 60th birthday, Trudy Mat. Inst. Steklova, 329, Steklov Math. Inst., Moscow, 2025, 132–164; Proc. Steklov Inst. Math., 329 (2025), 117–147