Cartier algebras through the lens of $p$-families

Abstract

We study $F$-graded systems of ideals in $R$, which are sequences of ideals giving rise to Cartier algebras on $R$. We identify how properties of these systems (or modifications of these systems) affect the singularity properties of the corresponding Cartier algebra. In particular, we show that in a Gorenstein and strongly $F$-regular local ring, strong $F$-regularity and $F$-splitting are the same for a special class of $F$-graded systems called $p$-families. Further, we make use of this and a new operation we introduce called $p$-stabilization to get a criterion that in a Gorenstein and strongly $F$-regular local ring, a system is strongly $F$-regular exactly when its $p$-stabilization is $F$-split. Finally, we associate a combinatorial object to systems built out of monomial ideals and show how this can help compute the $p$-stabilization.

22 pages, 1 figure. Comments welcome!