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Bibliographic Details
Main Author: Kir, Harun
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2602.14319
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author Kir, Harun
author_facet Kir, Harun
contents In 1994, Kani introduced an algebraic version of the Humbert invariant, known as the refined Humbert invariant. This invariant q_C is a positive definite quadratic form attached to a smooth curve C of genus 2. It serves as a vital tool, as many geometric properties of C are reflected in the arithmetic properties of q_C. When the Jacobian J_C of a genus 2 curve C is isogenous to a product of an elliptic curve with complex multiplication, the forms q_C have been completely classified recently. In this paper, building upon this classification, we present a constructive algorithm that produces J_C and a divisorial representative of a curve C of genus 2 such that its refined Humbert invariant q_C is equivalent to a given integral ternary quadratic form.
format Preprint
id arxiv_https___arxiv_org_abs_2602_14319
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Constructing genus 2 curves with given refined Humbert invariants
Kir, Harun
Number Theory
Algebraic Geometry
In 1994, Kani introduced an algebraic version of the Humbert invariant, known as the refined Humbert invariant. This invariant q_C is a positive definite quadratic form attached to a smooth curve C of genus 2. It serves as a vital tool, as many geometric properties of C are reflected in the arithmetic properties of q_C. When the Jacobian J_C of a genus 2 curve C is isogenous to a product of an elliptic curve with complex multiplication, the forms q_C have been completely classified recently. In this paper, building upon this classification, we present a constructive algorithm that produces J_C and a divisorial representative of a curve C of genus 2 such that its refined Humbert invariant q_C is equivalent to a given integral ternary quadratic form.
title Constructing genus 2 curves with given refined Humbert invariants
topic Number Theory
Algebraic Geometry
url https://arxiv.org/abs/2602.14319