4 problems

Let $K$ be a complete discrete valuation field of mixed characteristic $(0,p)$ with non-trivial valuation, let $M$ be a finite free differential module over $K[\![t]\!]_0$ admittin…

Let $A$ be a ring and let ${\mathcal C}$ be an $A$-coring, meaning an $A$-bimodule equipped with counit and comultiplication maps satisfying the coring axioms. The coring…

Let $n$ be a positive integer, let $\omega$ be the parameter in the Taft algebra, and define … An extension consists of a Frobenius automorphism $\phi$ and an element $\theta$; cal…

A differential equation is considered together with its solution space and the associated Frobenius action. A Frobenius structure means a structure expressing compatibility between…