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Genus 2 curves are useful in cryptography for both discrete-log based and pairing-based systems, but a method is required to compute genus 2 curves such that the Jacobian has a given number of points. Currently, all known methods involve…

Number Theory · Mathematics 2010-03-26 Eyal Z. Goren , Kristin E. Lauter

An important problem in computational arithmetic geometry is to find changes of coordinates to simplify a system of polynomial equations with rational coefficients. This is tackled by a combination of two techniques, called minimisation and…

Number Theory · Mathematics 2023-09-13 Tom Fisher , Mengzhen Liu

The purpose of this paper is to list the refined Humbert invariants for a given automorphism group of a curve $C/K$ of genus 2 over an algebraically closed field $K$ with characteristic $0$. This invariant is an algebraic generalization of…

Algebraic Geometry · Mathematics 2023-10-31 Harun Kir

We present a quasi-linear algorithm to compute isogenies between Jacobians of curves of genus 2 and 3 starting from the equation of the curve and a maximal isotropic subgroup of the l-torsion, for l an odd prime number, generalizing the…

Algebraic Geometry · Mathematics 2019-08-27 Enea Milio

We construct a birational model of the generalised Kummer fourfold of the Jacobian of a genus two curve, based on a geometric interpretation of the addition law on this Jacobian, obtained by the properties of the linear system of cubics on…

Algebraic Geometry · Mathematics 2025-05-23 Samuel Boissiere , Marc Nieper-Wisskirchen , Gregory Sankaran

In this paper we classify curves of genus two over a perfect field k of characteristic two. We find rational models of curves with a given arithmetic structure for the ramification divisor and we give necessary and sufficient conditions for…

Number Theory · Mathematics 2007-05-23 Gabriel Cardona , Enric Nart , Jordi Pujolas

We study the problem of efficiently constructing a curve C of genus 2 over a finite field F for which either the curve C itself or its Jacobian has a prescribed number N of F-rational points. In the case of the Jacobian, we show that any…

Number Theory · Mathematics 2019-02-20 Reinier Bröker , Everett W. Howe , Kristin E. Lauter , Peter Stevenhagen

We introduce a general abstract notion of fine compactified Jacobian for nodal curves of arbitrary genus. We focus on genus 1 and prove combinatorial classification results for fine compactified Jacobians in the case of a single nodal curve…

Algebraic Geometry · Mathematics 2022-03-01 Nicola Pagani , Orsola Tommasi

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…

Number Theory · Mathematics 2026-02-17 Harun Kir

We give a complete answer to the question of which polynomials occur as the characteristic polynomials of Frobenius for genus-2 curves over finite fields.

Number Theory · Mathematics 2010-01-23 Everett W. Howe , Enric Nart , Christophe Ritzenthaler

We give two characterizations of Jacobians of curves with involution having fixed points in the framework of two particular cases of Welter's trisecant conjecture. The geometric form of each of these characterizations is the statement that…

Algebraic Geometry · Mathematics 2021-09-28 Igor Krichever

Let $C$ be a smooth projective curve of genus $g \ge 1$ over a finite field $\F$ of cardinality $q$. In this paper, we first study $\#\J_C$, the size of the Jacobian of $C$ over $\F$ in case that $\F(C)/\F(X)$ is a geometric Galois…

Number Theory · Mathematics 2010-07-28 Maosheng Xiong 'and' Alexandru Zaharescu

We study the configurations of genus 2 curves on the Fano surfaces of cubic threefolds. We establish a link between some involutive automorphisms acting on such a surface S and genus 2 curves on S. We give a partial classification of the…

Algebraic Geometry · Mathematics 2010-02-25 Xavier Roulleau

We revisit and generalize some geometric techniques behind deterministic primality testing for some integer sequences using curves of genus 1 over finite rings. Subsequently we develop a similar primality test using the Jacobian of a genus…

Number Theory · Mathematics 2017-10-16 Eduardo Ruiz Duarte

Cais, Ellenberg and Zureick-Brown recently observed that over finite fields of characteristic two, all sufficiently general smooth plane projective curves of a given odd degree admit a non-trivial rational 2-torsion point on their Jacobian.…

Number Theory · Mathematics 2020-12-10 Wouter Castryck , Marco Streng , Damiano Testa

We prove that the geometric genus p of a curve in a very generic Jacobian of dimension g>3 satisfies either p=g or p>2g-3. This gives a positive answer to a conjecture of Naranjo and Pirola. For low values of g the second inequality can be…

Algebraic Geometry · Mathematics 2011-02-22 Valeria Ornella Marcucci

In this work we consider constructions of genus three curves $X$ such that $\mathrm{End}(\mathrm{Jac}(X)) \otimes Q$ contains the totally real cubic number field $Q(\zeta _ 7 + \overline{\zeta}_7)$. We construct explicit two-dimensional…

Algebraic Geometry · Mathematics 2014-11-11 J. William Hoffman , Zhibin Liang , Yukiko Sakai , Haohao Wang

Let $Y$ be a genus $2$ curve over $\mathbb Q$. We provide a method to systematically search for possible candidates of a prime $\ell\geq 3$ and a genus $1$ curve $X$ for which there exists a genus $3$ curve $Z$ over $\mathbb Q$ whose…

Number Theory · Mathematics 2025-08-05 Pitchayut Saengrungkongka , Noah Walsh

We describe an algorithm, based on the properties of the characteristic polynomials of Frobenius, to compute $\operatorname{End}_{\overline{K}}(A)$ when $A$ is the Jacobian of a nice genus-2 curve over a number field $K$. We use this…

Number Theory · Mathematics 2021-06-02 Davide Lombardo

In this work we propose an algorithm that numerically evaluates Kleinian hyperelliptic functions associated with a complex curve of genus 2. This algorithm is based upon constructing a sequence of curves with Richelot isogenous Jacobians…

Complex Variables · Mathematics 2026-03-25 Matvey Smirnov