arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1808.04520math.NT
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在产生孤立的$j$ -不变量的模曲线的水平上

On the level of modular curves that give rise to isolated $j$-invariants

Abbey Bourdon, Ozlem Ejder, Yuan Liu, Frances Odumodu, Bianca Viray

摘要:

我们说曲线$C$上的一个闭点$x$是散点的,如果$C$最多只有2/4个闭点的次数为$\operatorname{deg}(x)$,如果它不在由$\mathbb{P}^1$或正秩阿贝尔簇参数化的有效次数$d$因子族中,则$x$是孤立的(见第4节更精确的定义和散点是孤立的证明)。基于椭圆曲线有理挠率的分类问题,我们研究了模曲线$X_1(N)$上的零星点和孤立点。特别是,我们表明,任何非尖点非CM零星的,分别孤立的,点$x \in X_1(N)$映射到一个零星的,分别孤立的,点上的模块化曲线$X_1(d)$,其中$d$是有界的常数只取决于$j(x)$。同时,我们表明,$d$是有界的一个常数,只取决于程度的$\mathbb{Q}(j(x))$,所以特别是有界的程度,产生零星或孤立的点,只有100多个$j$ -不变量。

英文摘要:

We say a closed point $x$ on a curve $C$ is sporadic if $C$ has only finitely many closed points of degree at most $\operatorname{deg}(x)$ and that $x$ is isolated if it is not in a family of effective degree $d$ divisors parametrized by $\mathbb{P}^1$ or a positive rank abelian variety (see Section 4 for more precise definitions and a proof that sporadic points are isolated). Motivated by well-known classification problems concerning rational torsion of elliptic curves, we study sporadic and isolated points on the modular curves $X_1(N)$. In particular, we show that any non-cuspidal non-CM sporadic, respectively isolated, point $x \in X_1(N)$ maps down to a sporadic, respectively isolated, point on a modular curve $X_1(d)$, where $d$ is bounded by a constant depending only on $j(x)$. Conditionally, we show that $d$ is bounded by a constant depending only on the degree of $\mathbb{Q}(j(x))$, so in particular there are only finitely many $j$-invariants of bounded degree that give rise to sporadic or isolated points.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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