arXiv subjects

Luca Fiorindo

Publications and source records attributed to Luca Fiorindo.

7 recordsLinked to original sources

arXiv2026

Weighted Veronese Rings via Convex Semigroups

We determine properties of two-dimensional normal affine semigroup rings, and in particular of weighted Veronese rings, including determinantal presentation, Gr\"obner basis, graded Hilbert series and graded Betti numbers, the structure of their associated graded rings, and their Koszul property. We give examples in higher dimensions illustrating that the first and last properties may fail. Our approach leverages convex monomial ideals as introduced in Herzog-Qureshi-Saem(2019), which give rise to convex semigroups.

math.AC↗

arXiv2024

Asymptotic behaviour of Vasconcelos invariants for products and powers of graded ideals

Let $R$ be a commutative Noetherian $\mathbb{N}$-graded ring. Let $N\subseteq M$ be finitely generated $\mathbb{Z}$-graded $R$-modules. Let $I_1,\ldots,I_r$ be nonzero proper homogeneous ideals of $R$. Denote ${\bf I}^{\underline{n}}:=I_1^{n_1}\cdots I_r^{n_r}$ for $\underline{n}=(n_1,\dots,n_r)\in\mathbb{N}^r$. In this paper, we prove that the (local) Vasconcelos invariant of ${\bf I}^{\underline{n}}M/{\bf I}^{\underline{n}}N$ is eventually the minimum of finitely many linear functions in $\underline{n}$. The same holds for $M/{\bf I}^{\underline{n}}N$ under certain conditions. Some specific examples are provided, where these functions are not eventually linear in $\underline{n}$. However, when $R$ is a polynomial ring over a field, we show that the global Vasconcelos invariants of $R/{\bf I}^{\underline{n}}$ and ${\bf I}^{\underline{n}}/{\bf I}^{\underline{n}+\underline{1}}$ are, in fact, asymptotically linear in $\underline{n}$ with the leading coefficients given by the initial degrees of $I_1,\ldots,I_r$. The last result is surprising: It differs from the Castelnuovo-Mumford regularity, which is not always linear even over polynomial rings, as shown by Bruns-Conca.

math.AC↗

arXiv2024

On the asymptotic behaviour of the Vasconcelos invariant for graded modules

The notion of Vasconcelos invariant, known in the literature as v-number, of a homogeneous ideal in a polynomial ring over a field was introduced in 2020 to study the asymptotic behaviour of the minimum distance of projective Reed-Muller type codes. We initiate the study of this invariant for graded modules. Let $R$ be a Noetherian $\mathbb{N}$-graded ring, and $M$ be a finitely generated graded $R$-module. The v-number $v(M)$ can be defined as the least possible degree of a homogeneous element $x$ of $M$ for which $(0:_Rx)$ is a prime ideal of $R$. For a homogeneous ideal $I$ of $R$, we mainly prove that $v(I^nM)$ and $v(I^nM/I^{n+1}M)$ are eventually linear functions of $n$. In addition, if $(0:_M I)=0$, then $v(M/I^{n}M)$ is also eventually linear with the same leading coefficient as that of $v(I^nM/I^{n+1}M)$. These leading coefficients are described explicitly. The result on the linearity of $v(M/I^{n}M)$ considerably strengthens a recent result of Conca which was shown when $R$ is a domain and $M=R$, and Ficarra-Sgroi where the polynomial case is treated.

math.AC↗

arXiv2023

A Uniform Identification of Stable Sheaf Cohomology

This paper considers generalizations of certain arithmetic complexes appearing in the work of Raicu and VandeBogert in connection with the study of stable sheaf cohomology on flag varieties. Defined over the ring of integer valued polynomials, we prove an isomorphism of these complexes as conjectured by Gao, Raicu, and VandeBogert. In particular, this shows that a previously made identification between the stable sheaf cohomology of hook and two column partition Schur functors applied to the cotangent sheaf of projective space can be made to be uniform with respect to these complexes. These results are extended to the projective space defined over the integers.

math.AC↗

arXiv2023

Hilbert functions and Jordan type of Perazzo Artinian algebras

We study Hilbert functions, Lefschetz properties, and Jordan type of Artinian Gorenstein algebras associated to Perazzo hypersurfaces in projective space. The main focus lies on Perazzo threefolds, for which we prove that the Hilbert functions are always unimodal. Further we prove that the Hilbert function determines whether the algebra is weak Lefschetz, and we characterize those Hilbert functions for which the weak Lefschetz property holds. By example, we verify that the Hilbert functions of Perazzo fourfolds are not always unimodal. In the particular case of Perazzo threefolds with the smallest possible Hilbert function, we give a description of the possible Jordan types for multiplication by any linear form.

math.AC↗

arXiv2023

Perazzo 3-folds and the weak Lefschetz property

We deal with Perazzo 3-folds in $\mathbb P^4$, i.e. hypersurfaces $X=V(f)\subset \mathbb P^4$ of degree $d$ defined by a homogeneous polynomial $f(x_0,x_1,x_2,u,v)=p_0(u,v)x_0+p_1(u,v)x_1+p_2(u,v)x_2+g(u,v)$, where $p_0,p_1,p_2$ are algebraically dependent but linearly independent forms of degree $d-1$ in $u,v$, and $g$ is a form in $u,v$ of degree $d$. Perazzo 3-folds have vanishing hessian and, hence, the associated graded artinian Gorenstein algebra $A_f$ fails the strong Lefschetz property. In this paper, we determine the maximum and minimum Hilbert function of $A_f$ and we prove that if $A_f$ has maximal Hilbert function it fails the weak Lefschetz property, while it satisfies the weak Lefschetz property when it has minimum Hilbert function. In addition, we classify all Perazzo 3-folds in $\mathbb P^4$ such that $A_f$ has minimum Hilbert function.

math.AG↗

arXiv2022

Polynomials with vanishing Hessian and Lefschetz properties

The aim is to study Perazzo hypersurfaces $X=V(F)\subseteq\mathbb{P}(K^5)$, defined by $F(x_0,x_1,x_2,u,v) = p_0(u,v)x_0+p_1(u,v)x_1+p_2(u,v)x_2+g(u,v)$, where $p_0,p_1,p_2$ are algebraically dependent, but linearly independent forms of degree $d-1$ in $u,v$, and $g$ is a form in $u,v$ of degree $d$. These hypersurfaces are the "building blocks" for all possible hypersuface in $\mathbb{P}^4$ with vanishing Hessian. A minimal and a maximal Hilbert vector is found for the associated Artinian Gorenstein $K$-algebras $A_F$: in the minimal case they satisfy the Weak Lefschetz property, but in the maximal case they don't. Furthermore, we classify all Perazzo $3$-folds with minimal $h$-vector. We also summarise basic knowledge and already known results about hypersurfaces with vanishing Hessian and their geometry in low dimension, and also about Artinian Gorenstein $K$-algebras.

math.AG↗