arXiv subjects

Przemysław Grabowski

Publications and source records attributed to Przemysław Grabowski.

4 recordsLinked to original sources

arXiv2026

On Algebraic Integrability of Vector Fields with Rational Function Coefficients that Separate Variables

We work over a field of characteristic zero - primarily over an algebraic closure of the field of rational numbers. We prove a necessary and sufficient condition for a vector field whose coefficients are rational functions separating variables to be algebraically integrable, that is, the subring of rational functions killed by this vector field, its ring of first integrals, is of maximal possible dimension. We do it arithmetically by reducing the vector field modulo almost all primes. In particular, we verify the generalized Grothendieck--Katz p-curvature conjecture for foliations defined by these vector fields. Finally, we use the outcome of that verification to provide explicit formulas for coefficients of all algebraically integrable vector fields separating variables, and their first integrals.

math.AG↗

arXiv2025

Power Towers: Purely Inseparable Galois Theory and Foliations in Positive Characteristic

We build a purely inseparable Galois theory using non-derived commutative algebra. Our theory works on fields and on normal varieties. It says that a purely inseparable morphism corresponds to a finite (saturated) subalgebra of differential operators. Our approach unifies most of the literature about purely inseparable morphisms and shows new research directions. Indeed, our theory extends to a theory that covers all (saturated) subalgebras of differential operators. The extended theory gives a correspondence between the subalgebras and a new notion of \textbf{power towers}. A power tower is an object analogous to a foliation from differential geometry. In particular, it admits its own versions of many key results about foliations, such as a ``fibrations inject into foliations'' and a ``Frobenius theorem''. The latter has a nontrivial twist: the local structure is trivial at every point, but it may differ between points! In general, our analogy between power towers and foliations explains why purely inseparable morphisms are foliation-like, because these morphisms are power towers in an explicit way. Finally, we use our theory to produce a formula for pullbacks of canonical divisors for arbitrary purely inseparable morphisms. We use it to conclude some ``not-L{ü}roth theorems'': if the characteristic is high enough, then any variety purely inseparably covered by an $n$-dimensional projective space has Iitaka dimension equal to $-\infty$ or $n$, i.e., it is not zero.

math.AG↗

arXiv2024

Canonical liftings of Calabi--Yau hypersurfaces: Dwork hypersurfaces

We explicitly compute canonical liftings modulo $p^2$ in a sense of Achinger--Zdanowicz of Dwork hypersurfaces. The computation involves studying a compatibility between Hodge filtrations and a crystalline Frobenius. In particular, remarkably, we explicitly compute a partial data of the crystalline Frobenius modulo $p^2$.

math.AG↗

arXiv2018

Finite orthogonal groups and periodicity of links

For a prime number $q\neq 2$ and $r>0$ we study, whether there exists an isometry of order $q^r$ acting on a free $\mathbb{Z}_{p^k}$-module equipped with a scalar product. We investigate, whether there exists such an isometry with no non-zero fixed points. Both questions are completely answered in this paper if $p\neq 2,q$. As an application we refine Naik's criterion for periodicity of links in $S^3$. The periodicity criterion we obtain is effectively computable and gives concrete restrictions for periodicity of low-crossing knots.

math.GT↗