What is known and not known about rational points of modular curves? What are some good references?

  • 4
    $\begingroup$ Could you make the question more specific? Do you mean $\mathbb{Q}$ or an arbitrary number field or what? Which modular curves $X_0(N),X_1(N),X(N)$ or some other? Good reference is Mazur, B., Modular curves and the Eisenstein ideal. Inst. Hautes Études Sci. Publ. Math. No. 47 (1977), 33--186. $\endgroup$ Commented Apr 25, 2011 at 18:42
  • 3
    $\begingroup$ Loic Merel's work from the mid-90s generalises some of Mazur's results to arbitrary number fields. See also Edixhoven's Seminaire Bourbaki talk from around the same time. But this question is ridiculously vague. $\endgroup$ Commented Apr 25, 2011 at 18:54
  • 3
    $\begingroup$ "What is known?" A lot; "and not known?" Also a lot. $\endgroup$
    – Olivier
    Commented Apr 25, 2011 at 20:49
  • 1
    $\begingroup$ A nice reference for Merel's result is the Clay Proceedings: math.univ-bpclermont.fr/~rebolledo/page-fichiers/… It also touches on related work of Mazur, Kamienny, Kenku, Momose, Parent and others. If we allow ourselves to move slightly outside the classical modular curves, we get lots of other interesting results, including the Bilu-Parent result on $X_{split}(p)$. $\endgroup$
    – stankewicz
    Commented Apr 25, 2011 at 21:57

1 Answer 1


Dear Dick,

I am going to interpret rational points to mean points over $\mathbb Q$.

Given this, Mazur's Eisenstein ideal paper, his rational isogenies paper, and various surveys he wrote around that time (mid-to-late 1970s) give a good description (and also prove the most of the key results).

Ogg also wrote surveys in the early 70s, making conjectures which Mazur then proved, which are very helpful. You'll easily find them on mathscinet (as you will with Mazur's papers and surveys).

Best wishes,



Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.