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Betti numbers of full Perazzo algebras

Rosa Maria Miró-Roig, Josep Pérez

TL;DR

This work identifies a structural mechanism for full Perazzo algebras: each such artinian Gorenstein algebra $A_F$ is the doubling of a $0$-dimensional scheme $Z_F$ consisting of $n+1$ double points, and it derives explicit graded Betti numbers for a minimal free resolution of $A_F$ by combining the resolution of $R/I(Z_F)$ with the doubling construction via a mapping cone. The key method hinges on expressing the Macaulay dual generator in a form compatible with doubling and then transferring Betti information through homological constructions, yielding a self-dual Betti table whose nonzero entries in the first nonzero row have closed-form binomial expressions in terms of $d$, $n$, and $m$. These results illuminate Lefschetz-type properties of Perazzo algebras and pave the way for characterizing which Perazzo algebras arise as doublings of zero-dimensional schemes. The findings provide concrete, computable invariants and suggest natural generalizations to broader classes of Perazzo algebras.

Abstract

In this paper we prove that any full Perazzo algebra $A_F$, whose Macaulay dual generator is a Perazzo form $F\in K[X_0,\dots,X_n,U_1,\dots,U_m]_d$ with $n+1 = \binom{d+m-2}{m-1}$, is the doubling of a 0-dimensional scheme in $\PP^{n+m}$ and we compute the graded Betti numbers of a minimal free resolution of $A_F$.

Betti numbers of full Perazzo algebras

TL;DR

This work identifies a structural mechanism for full Perazzo algebras: each such artinian Gorenstein algebra is the doubling of a -dimensional scheme consisting of double points, and it derives explicit graded Betti numbers for a minimal free resolution of by combining the resolution of with the doubling construction via a mapping cone. The key method hinges on expressing the Macaulay dual generator in a form compatible with doubling and then transferring Betti information through homological constructions, yielding a self-dual Betti table whose nonzero entries in the first nonzero row have closed-form binomial expressions in terms of , , and . These results illuminate Lefschetz-type properties of Perazzo algebras and pave the way for characterizing which Perazzo algebras arise as doublings of zero-dimensional schemes. The findings provide concrete, computable invariants and suggest natural generalizations to broader classes of Perazzo algebras.

Abstract

In this paper we prove that any full Perazzo algebra , whose Macaulay dual generator is a Perazzo form with , is the doubling of a 0-dimensional scheme in and we compute the graded Betti numbers of a minimal free resolution of .
Paper Structure (9 sections, 9 theorems, 55 equations)

This paper contains 9 sections, 9 theorems, 55 equations.

Key Result

Lemma 3.1

Let $A=R/I$ be an artinian algebra of codimension $c$, socle degree $e\ge 3$ and $h$-vector $(1,c,1,\cdots ,1)$. It holds: (1) Up to change of coordinates: $I=\langle x_{c-1}^{e+1}, x_ix_j \mid 0\le i,j\le c-1 \text{ and } (i,j)\ne (c-1,c-1) \rangle$ (2) The Betti table of $A$ is: where

Theorems & Definitions (31)

  • Definition 2.1
  • Definition 2.2
  • Definition 2.3
  • Example 2.4
  • Definition 2.5
  • Definition 2.6
  • Example 2.7
  • Lemma 3.1
  • proof
  • Proposition 3.3
  • ...and 21 more