Searcharxiv⌕ Search

arXiv · math/9901038

Algebraic families of nonzero elements of Shafarevich-Tate groups

Abstract

We show that there exist non-trivial families of algebraic varieties for which all the fibers above rational points (or even above points of odd degree) are torsors of abelian varieties representing nonzero elements of their Shafarevich-Tate groups.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Jean-Louis Colliot-Thelene, Bjorn Poonen. 1999-01-09. Algebraic families of nonzero elements of Shafarevich-Tate groups. https://doi.org/10.1090/s0894-0347-99-00315-x

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

Qin's Algorithm, Continued Fractions and 2-dimensional Lattices

In his ``Mathematical Treatise in Nine Sections''(1247), Jiushao Qin introduced ``the Dayan method of deriving unity'' for computing modular inverses, an essential component of his treatment of the Chinese remainder theorem. A distinctive feature of Qin's algorithm is its use of a state consisting of four nonnegative integers arranged in a matrix. In this paper, we investigate the mathematical structure of these states and their connections with continued fractions and two-dimensional lattices. By introducing a signed version of the state, we obtain a natural matrix representation that reveals the convergents of continued fractions and gives direct derivations of several classical results. We then show that the signed states form bases of a family of two-dimensional lattices arising from modular congruences. In particular, we prove that a shortest lattice vector can be obtained from the rows of a signed state or their sum or difference. We also study the monotonicity of the inner products of the state vectors and discuss a subsequent result that locates a shortest vector in one of two consecutive states. It is surprising that a shortest lattice vector is found in a highly structure sequence of states. These results demonstrate that the state structure of Qin's algorithm provides a unified framework for understanding modular inversion, continued fractions, and shortest vectors in two-dimensional lattices.

math.NT↗

The symmetrized sum of finite $q$-multiple harmonic sums with one exceptional index

In this paper, we give explicit expressions for $q$-harmonic sums on $1-\cdots-1,A,1-\cdots-1$ indices. The case $A=1$ has been extensively studied, and a variety of identities, explicit evaluations, and structural properties are known. Likewise, numerous explicit evaluations are available for $q$-multiple zeta values and $q$-harmonic sums with uniform indices $A-\cdots-A$. Although several methods are available for treating non-uniform indices, explicit evaluations for the pattern $1-\cdots-1,A,1-\cdots-1$ remain comparatively scarce. The case $A=2$ was settled only recently. In this paper, we extend this framework to the general case $A\ge3$ as the total sum with the theory of the elementary symmetric functions, though we do not generally evaluate each summand at a prescribed position of $A$. We obtain explicit formulas in terms of binomial coefficients and degenerate Bernoulli numbers. Some expressions about $2-\cdots-2,A,2-\cdots-2$ are also shown.

math.NT↗