Let $S$ be a finite set of primes. An elliptic curve $E/\mathbb{Q}$ is said to have good reduction outside $S$ if its minimal discriminant (equivalently, its conductor) is only divisible by primes in $S$. This table lists the numbers of elliptic curves $E/\mathbb{Q}$ with good reduction outside $S$ counted in two different ways: up to $\mathbb{Q}$-isomorphism, and up to $\overline{\mathbb{Q}}$-isomorphism.
Parameters
$S$
— set of primes
Comments
(1)
Elliptic curves over $\mathbb{Q}$ with good reduction outside of the first $n$ have been computed by several authors: $n=0$ by Tate (see [6]), $n=1$ by Ogg [6], $n=2$ by Coghlan [3] and Stephens [7], $n=3,4,5$ by von Känel and Matschke [4] and Bennett, Gherga and Rechnitzer [1], $n=6$ heuristically by Best and Matschke [2], $n=7,8,9^*$ by Matschke [9] ($n=9$ assumes GRH).
References
[1]
Michael A. Bennett, Adela Gherga, and Andrew Rechnitzer, "Computing elliptic curves over Q". Math. Comp., 88(317):1341–1390, 2019.
[2]
A. Best, B. Matschke, "Elliptic curves with good reduction outside of the first six primes". 2020 (arXiv) (github)
[3]
Francis Coghlan, "Elliptic Curves with Conductor $2^m 3^n$". Ph.D. thesis, Manchester, England, 1967.
[4]
R. von Känel, B. Matschke, "Solving S-unit, Mordell, Thue, Thue-Mahler and generalized Ramanujan-Nagell equations via Shimura-Taniyama conjecture". 2016 (arXiv) (github)
[5]
Angelos Koutsianas, "Computing all elliptic curves over an arbitrary number field with prescribed primes of bad reduction". Exp. Math., 28(1):1–15, 2019. (arXiv) (github)
[6]
Andrew P. Ogg, "Abelian curves of 2-power conductor". Math. Proc. Camb. Philos. Soc., 62(2):143–148, 1966.
[7]
Nelson M. Stephens, "The Birch Swinnerton-Dyer Conjecture for Selmer curves of positive rank". Ph.D. Thesis, Manchester, 1965.
Reliability: Assumes GRH if $23\in S$. Needs to be recomputed to be provably correct (see readme.md in [9]).
How well the digits are known: proven
How they were obtained: A fixed-precision value wrapped in an interval field, which records no error of its own. The working precision was half as many digits again as were written, and nothing checked that the margin sufficed.