Skip to main content
17 events
when toggle format what by license comment
Jul 24, 2018 at 22:40 vote accept Alm
Jul 24, 2018 at 22:40 vote accept Alm
Jul 24, 2018 at 22:40
Jul 23, 2018 at 20:22 vote accept Alm
Jul 24, 2018 at 22:40
Jul 21, 2018 at 7:29 answer added Bombyx mori timeline score: 1
Jul 19, 2018 at 19:48 comment added Watson Possibly related: math.stackexchange.com/questions/369723
Jul 19, 2018 at 8:23 comment added Alm Good point. Let me add that the multiplication law should be a rational function.
Jul 19, 2018 at 8:21 answer added Ben McKay timeline score: 5
Jul 19, 2018 at 8:12 answer added user19475 timeline score: 18
Jul 19, 2018 at 8:05 answer added Francesco Polizzi timeline score: 12
Jul 19, 2018 at 8:01 answer added jmc timeline score: 7
Jul 19, 2018 at 7:54 comment added jmc By the way: there exist elliptic curves over the rationals that have finitely many rational points.
Jul 19, 2018 at 7:53 comment added jmc Every non-empty set can be endowed with a group structure. But that is not (should not be?) what you are after. I do not see why you would be interested in putting a group structure on the rational points of some variety if you don't ask for some compatibility with the geometric structure. (It is like have a set, endowing it with a group structure and a topology, but not caring whether multiplication is continuous...)
Jul 19, 2018 at 7:47 comment added user19475 You could also look at the tangent bundle or use the Lefschetz fixed point formula applied to the translation by the unit section.
Jul 19, 2018 at 7:46 comment added Alm Does this property not hold for curves with genus greater than 1? In the case, one could have a group over the rationals that is not compatible with group over extended fields. At least in principle.
Jul 19, 2018 at 7:20 comment added Qiaochu Yuan It's not just that there's a group structure on the rational points; e.g. there's a group structure on the points over any field extension $K$ of the ground field, and these group structures are compatible with inclusions of field extensions. More precisely, elliptic curves are what are called group schemes.
Jul 19, 2018 at 7:20 comment added KConrad A curve of genus $g\geq 1$has an associated group (abelian variety), its Jacobian variety, of dimension $g$. For $g>1$ the Jacobian is not a curve.
Jul 19, 2018 at 7:15 history asked Alm CC BY-SA 4.0