scholarly journals A positive proportion of locally soluble hyperelliptic curves over $\mathbb {Q}$ have no point over any odd degree extension

2016 ◽  
Vol 30 (2) ◽  
pp. 451-493 ◽  
Author(s):  
Manjul Bhargava ◽  
Benedict H. Gross ◽  
Xiaoheng Wang
Keyword(s):  
Hyperelliptic Curves ◽  
Positive Proportion ◽  
Odd Degree

scholarly journals Brauer–Manin obstruction and families of generalised Châtelet surfaces over number fields

2019 ◽  
Vol 15 (02) ◽  
pp. 289-308
Author(s):  
Francesca Balestrieri
Keyword(s):  
Sufficient Conditions ◽  
Number Fields ◽  
Specific Form ◽  
Hasse Principle ◽  
Galois Extensions ◽  
Positive Proportion ◽  
Odd Degree

Over infinitely many number fields [Formula: see text] (including all finite Galois extensions [Formula: see text] of odd degree unramified at 2), we give general sufficient conditions in order for the generalised Châtelet surfaces [Formula: see text] over [Formula: see text] associated to the normic equation [Formula: see text], where [Formula: see text] has a specific form and [Formula: see text] is even and arbitrarily large, to have the property that [Formula: see text] but [Formula: see text]. We also give general sufficient conditions in order for the generalised Châtelet surfaces [Formula: see text] over [Formula: see text] of the same form as above to have the property that [Formula: see text] and [Formula: see text]. As an application, we prove that, for a certain family of generalised Châtelet surfaces over [Formula: see text], a positive proportion (but not 100[Formula: see text]) of its members exhibits a violation of the Hasse principle explained by the Brauer–Manin obstruction.

scholarly journals ON THE MERTENS CONJECTURE FOR FUNCTION FIELDS

2014 ◽  
Vol 10 (02) ◽  
pp. 341-361 ◽  
Author(s):  
PETER HUMPHRIES
Keyword(s):  
Function Fields ◽  
Hyperelliptic Curves ◽  
Natural Analogue ◽  
Global Function ◽  
Positive Proportion ◽  
Global Function Fields

We study the natural analogue of the Mertens conjecture in the setting of global function fields. Building on the work of Cha, we show that most hyperelliptic curves do not satisfy the Mertens conjecture, but that if we modify the Mertens conjecture to have a larger constant, then this modified conjecture is satisfied by a positive proportion of hyperelliptic curves.

scholarly journals Rational points on hyperelliptic curves having a marked non-Weierstrass point

2017 ◽  
Vol 154 (1) ◽  
pp. 188-222
Author(s):  
Arul Shankar ◽  
Xiaoheng Wang
Keyword(s):  
Weierstrass Point ◽  
Hyperelliptic Curves ◽  
Rational Points ◽  
Selmer Groups ◽  
Automorphic Representations ◽  
The Family ◽  
Odd Degree ◽  
Fundamental Research ◽  
Average Size ◽  
Fixed Genus

In this paper, we consider the family of hyperelliptic curves over$\mathbb{Q}$having a fixed genus$n$and a marked rational non-Weierstrass point. We show that when$n\geqslant 9$, a positive proportion of these curves have exactly two rational points, and that this proportion tends to one as$n$tends to infinity. We study rational points on these curves by first obtaining results on the 2-Selmer groups of their Jacobians. In this direction, we prove that the average size of the 2-Selmer groups of the Jacobians of curves in our family is bounded above by 6, which implies a bound of$5/2$on the average rank of these Jacobians. Our results are natural extensions of Poonen and Stoll [Most odd degree hyperelliptic curves have only one rational point, Ann. of Math. (2)180(2014), 1137–1166] and Bhargava and Gross [The average size of the 2-Selmer group of Jacobians of hyperelliptic curves having a rational Weierstrass point, inAutomorphic representations and$L$-functions, Tata Inst. Fundam. Res. Stud. Math., vol. 22 (Tata Institute of Fundamental Research, Mumbai, 2013), 23–91], where the analogous results are proved for the family of hyperelliptic curves with a marked rational Weierstrass point.

scholarly journals Optimized CSIDH Implementation Using a 2-Torsion Point

Cryptography ◽  
2020 ◽  
Vol 4 (3) ◽  
pp. 20 ◽  
Author(s):  
Donghoe Heo ◽  
Suhri Kim ◽  
Kisoon Yoon ◽  
Young-Ho Park ◽  
Seokhie Hong
Keyword(s):  
Elliptic Curve ◽  
Group Action ◽  
Large Degree ◽  
Transitive Group ◽  
Optimization Method ◽  
Torsion Point ◽  
Torsion Points ◽  
Diffie Hellman ◽  
Odd Degree ◽  
Montgomery Curve

The implementation of isogeny-based cryptography mainly use Montgomery curves, as they offer fast elliptic curve arithmetic and isogeny computation. However, although Montgomery curves have efficient 3- and 4-isogeny formula, it becomes inefficient when recovering the coefficient of the image curve for large degree isogenies. Because the Commutative Supersingular Isogeny Diffie-Hellman (CSIDH) requires odd-degree isogenies up to at least 587, this inefficiency is the main bottleneck of using a Montgomery curve for CSIDH. In this paper, we present a new optimization method for faster CSIDH protocols entirely on Montgomery curves. To this end, we present a new parameter for CSIDH, in which the three rational two-torsion points exist. By using the proposed parameters, the CSIDH moves around the surface. The curve coefficient of the image curve can be recovered by a two-torsion point. We also proved that the CSIDH while using the proposed parameter guarantees a free and transitive group action. Additionally, we present the implementation result using our method. We demonstrated that our method is 6.4% faster than the original CSIDH. Our works show that quite higher performance of CSIDH is achieved while only using Montgomery curves.

scholarly journals Coleman integration for even-degree models of hyperelliptic curves

2015 ◽  
Vol 18 (1) ◽  
pp. 258-265 ◽  
Author(s):  
Jennifer S. Balakrishnan
Keyword(s):  
Number Theory ◽  
Computer Science ◽  
Hyperelliptic Curves ◽  
Open Book ◽  
Line Integral ◽  
Book Series ◽  
Numerical Examples ◽  
Lecture Notes ◽  
Integration Algorithms ◽  
Mathematical Sciences

The Coleman integral is a $p$-adic line integral that encapsulates various quantities of number theoretic interest. Building on the work of Harrison [J. Symbolic Comput. 47 (2012) no. 1, 89–101], we extend the Coleman integration algorithms in Balakrishnan et al. [Algorithmic number theory, Lecture Notes in Computer Science 6197 (Springer, 2010) 16–31] and Balakrishnan [ANTS-X: Proceedings of the Tenth Algorithmic Number Theory Symposium, Open Book Series 1 (Mathematical Sciences Publishers, 2013) 41–61] to even-degree models of hyperelliptic curves. We illustrate our methods with numerical examples computed in Sage.

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