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20112026
most citedA GIT interpretration of the Harder-Narasimhan filtration

16 citations · 51 across the 15 of their papers we have counts for

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math.AG2026

Stringy invariants for abelian character varieties

Carlos Florentino, Ángel González-Prieto, Alfonso Zamora

We compute all stringy invariants, encoding orbifold cohomology numbers, of (the normalization of) the identity component of -character varieties of free abelian groups and of m…

math.AG2026

-polynomials of character varieties

Alfonso Zamora

These lecture notes contain the material presented at one of the mini-courses of the Workshop on Character Varieties and Higgs Bundles held in Liberia, Guanacaste, Costa Rica, in A…

math.AG2026

Segre invariants of principal bundles over a curve

George H. Hitching, Alfonso Zamora

For a vector bundle over a curve , the Segre invariant encodes the maximal degree attained by rank subbundles of . The functions define stratification…

math.AG2024

Root data in character varieties

Ángel González-Prieto, Alfonso Zamora

Given an algebraic reductive group over an algebraically closed field of characteristic zero and a finitely generated group, we provide a stratification of the -characte…

math.AG2023

A guide to moduli theory beyond GIT

Tomás L. Gómez, Andres Fernández Herrero, Alfonso Zamora

In this survey we provide an overview of some recent developments in the construction of moduli spaces using stack-theoretic techniques. We will also explain the analogue of Harder…

math.AG2021

The moduli stack of principal -sheaves and Gieseker-Harder-Narasimhan filtrations

Tomás L. Gómez, Andres Fernandez Herrero, Alfonso Zamora

Let X be a smooth projective variety and let G be a connected reductive group, both defined over a field of characteristic 0. Given a faithful representation of G into a produc…

math.AG2020★ 1 cited

On Hodge polynomials of Singular Character Varieties

Carlos Florentino, Azizeh Nozad, Jaime Silva +1

Let be the -character variety of , where is a complex reductive group and a finitely presented group. We introduce new techni…

math.AG2019★ 14 cited

Serre polynomials of - and -character varieties of free groups

Carlos Florentino, Azizeh Nozad, Alfonso Zamora

Let be a complex reductive group and denote the -character variety of the free group of rank . Using geometric methods, we prove that $E(\mathcal{X}_{r…

math.AG2019★ 2 cited

Generating series for the -polynomials of -character varieties

Carlos Florentino, Azizeh Nozad, Alfonso Zamora

With G=GL(n,C), let be the G-character variety of a given finitely presented group , and let be the locus of irred…

math.AG2017

Generating sets for Clifford Algebras

Brian Sittinger, Ricardo Suárez, Alfonso Zamora

The aim of this paper is to find generating sets of commuting involutions and use them to explicitly construct minimal representations of Clifford algebras . By result…

math.AG2015★ 2 cited

Stability conditions and related filtrations for -constellations

Ronan Terpereau, Alfonso Zamora

Given an infinite reductive algebraic group , we consider -equivariant coherent sheaves with prescribed multiplicities, called -constellations, for which two stability…

math.AG2014

On the Gieseker Harder-Narasimhan filtration for principal bundles

Indranil Biswas, Alfonso Zamora

We give an example of an orthogonal bundle where the Harder-Narasimhan filtration, with respect to Gieseker semistability, of its underlying vector bundle does not correspond to an…

math.AG2014★ 2 cited

GIT characterizations of Harder-Narasimhan filtrations

Alfonso Zamora

This Ph.D. thesis studies the relation between the Harder-Narasimhan filtration and a notion of GIT maximal unstability. When constructing a moduli space by using Geometric Invaria…

math.AG2013★ 3 cited

Harder-Narasimhan filtration for rank 2 tensors and stable coverings

Alfonso Zamora

We construct a Harder-Narasimhan filtration for rank tensors, where there does not exist any such notion a priori, as coming from a GIT notion of maximal unstability. The filtr…

math.AG2012★ 11 cited

On the Harder-Narasimhan filtration for finite dimensional representations of quivers

Alfonso Zamora

We prove that the Harder-Narasimhan filtration for an unstable finite dimensional representation of a finite quiver coincides with the filtration associated to the 1-parameter subg…

math.AG2011★ 16 cited

A GIT interpretration of the Harder-Narasimhan filtration

Tomas L. Gomez, Ignacio Sols, Alfonso Zamora

An unstable torsion free sheaf on a smooth projective variety gives a GIT unstable point in certain Quot scheme. To a GIT unstable point, Kempf associates a "maximally destabilizin…