arXiv subjects

Augustinas Jacovskis

Publications and source records attributed to Augustinas Jacovskis.

5 recordsLinked to original sources

arXiv2026

Brill-Noether reconstruction of index one prime Fano threefolds

We show by a uniform argument that every index one prime Fano threefold $X$ of genus $g\geq 6$ can be reconstructed as a Brill-Noether locus inside a Bridgeland moduli space of stable objects in the Kuznetsov component $\mathcal{K}u(X)$. As an application, we verify Mukai's conjecture on the existence of dual embeddings of $X$. Moreover, we establish a refined categorical Torelli theorem for $X$ and classify autoequivalences of $\mathcal{K}u(X)$. We also give an alternative disproof of Kuznetsov's Fano threefold conjecture.

math.AG↗

arXiv2026

Categorical Torelli theorems for higher Picard rank Fano double covers

We prove categorical Torelli theorems for four families of Fano double covers with Picard rank greater than 1. Among these is the family of Verra fourfolds. The other three families manifest as double covers of Fano threefolds, branched in anticanonical K3 surfaces. For the three families of threefolds, our proof is based on reducing equivalences between the Kuznetsov components of Fano threefolds in the same deformation family to derived equivalences of their respective K3 branch divisors, and deducing that the resulting isomorphism of branch divisors gives rise to an isomorphism of the Fano threefolds for each family. For Verra fourfolds, we show that an equivalence of their Kuznetsov components induces an isomorphism of the branch divisors using the theory of 2-torsion Brauer classes on K3 surfaces.

math.AG↗

arXiv2024

Categorical Torelli theorems for Gushel-Mukai threefolds

We show that a general ordinary Gushel-Mukai(GM) threefold $X$ is reconstructed from the Kuznetsov component $\mathcal{K}u(X)$ together with an extra data coming from tautological sub-bundle of Grassmannian $\mathrm{Gr}(2,5)$. We also prove that $\mathcal{K}u(X)$ determines birational isomorphism class of $X$, while $\mathcal{K}u(X')$ determines the isomorphism class of a general special GM threefold $X'$. As an application, we prove a conjecture of Kuznetsov-Perry in dimension three under a mild assumption. Finally, we use $\mathcal{K}u(X)$ to restate a conjecture of Debarre-Iliev-Manivel regarding fibers of the period map for ordinary GM threefolds.

math.AG↗

arXiv2023

Cyclic covers: Hodge theory and categorical Torelli theorems

Let $Y$ admit a rectangular Lefschetz decomposition of its derived category, and consider a cyclic cover $X\to Y$ ramified over a divisor $Z$. In a setting not considered by Kuznetsov and Perry, we define a subcategory $\mathcal{A}_Z$ of the equivariant derived category of $X$ which contains, rather than is contained in, $\mathrm{D}^{\mathrm{b}}(Z)$. We then show that the equivariant category of the Kuznetsov component of $X$ is decomposed into copies of $\mathcal{A}_Z$. As an application, we relate $\mathcal{A}_Z$ with the cohomology of $Z$ under some numerical assumptions. In particular, we obtain categorical Torelli theorems for the lowest degree prime Fano threefolds of index 1 and 2.

math.AG↗

arXiv2023

Infinitesimal categorical Torelli theorems for Fano threefolds

Let $X$ be a smooth Fano variety and $\mathcal{K}u(X)$ the Kuznetsov component. Torelli theorems for $\mathcal{K}u(X)$ says that it is uniquely determined by a polarized abelian variety attached to it. An infinitesimal Torelli theorem for $X$ says that the differential of the period map is injective. A categorical variant of infinitesimal Torelli theorem for $X$ says that the morphism $H^1(X,T_X)\xrightarrowη HH^2(\mathcal{K}u(X))$ is injective. In the present article, we use the machinery of Hochschild (co)homology to relate the three Torelli-type theorems for smooth Fano varieties via a commutative diagram. As an application, we first prove infinitesimal categorical Torelli theorem for a class of prime Fano threefolds. Then we prove a restatement of the Debarre-Iliev-Manivel conjecture infinitesimally.

math.AG↗