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Rational functions on elliptic curves over global fields with given support

Let $E$ be an elliptic curve over a global field $k$. Let $x_1, \dots, x_r$ be a set of generators of $E(k) / E(k)_{tor}$ (or more generally, a $\mathbb Q$-basis of $E(k)_{\mathbb Q}$), and let $x_0$ ...
yoyo's user avatar
  • 77
0 votes
0 answers
132 views

How near are a groupoid and its 'preorderification'?

As remarks, a groupoid is a category with only (categorical) isomorphisms as its morphisms and a preorder is a category only having one morphism between each object. If we choose one isomorphism by ...
categoricalequivalent's user avatar
1 vote
0 answers
89 views

Generic reducedness of geometric generic fibre

Let $f:X\to Y$ be a surjective morphism between two projective schemes over a field of characteristic $p>0$. Also assume that $X$ is smooth,$Y$ smooth & irreducible and $f_*\mathcal{O}_X=\...
user267839's user avatar
  • 5,986
3 votes
0 answers
66 views

p-torsion in the Tate-Shafarevich group of supersingular elliptic curves

Let $E$ be a supersingular elliptic curve over $\mathbb{F}_p(t)$. Is something known on the $p$-torsion of the Tate–Shafarevich group in this case? In particular, I would like to know if (or if known ...
user 123935's user avatar
3 votes
0 answers
36 views

Avoiding class/unit group computation when computing $p$-Selmer groups

Let $K$ be a number field, $S$ be a finite set of places of $K$, and $K(S,p)$ be the $p$-Selmer group of the $S$-integers of $K$, that is the set of nonzero elements of $K$ modulo $p$-th powers whose ...
Oisín Robinson's user avatar
0 votes
0 answers
58 views

Given $N=pq$, with what complexity we can find integer $a : q-\sqrt{q} < a <q+\sqrt{q}$?

Related to open problem and this question. Let $N=p q$ be integer with unknown factorization. Q1 Given $N=pq$, with what complexity we can find integer $a : q-\sqrt{q} < a <q+\sqrt{q}$? Assume ...
joro's user avatar
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