Congruent elliptic curves with non-trivial Shafarevich-Tate groups: Distribution part |
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Authors: | ZhangJie Wang |
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Affiliation: | 1.Yau Mathematical Sciences Center,Tsinghua University,Beijing,China |
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Abstract: | Given a large positive number x and a positive integer k, we denote by Q k(x) the set of congruent elliptic curves E (n): y 2 = z 3 ? n 2 z with positive square-free integers n ≤ x congruent to one modulo eight, having k prime factors and each prime factor congruent to one modulo four. We obtain the asymptotic formula for the number of congruent elliptic curves E (n) ∈ Q k(x) with Mordell-Weil ranks zero and 2-primary part of Shafarevich-Tate groups isomorphic to (?/2?)2. We also get a lower bound for the number of E (n) ∈ Q k(x) with Mordell-Weil ranks zero and 2-primary part of Shafarevich-Tate groups isomorphic to (?/2?)4. The key ingredient of the proof of these results is an independence property of residue symbols. This property roughly says that the number of positive square-free integers n ≤ x with k prime factors and residue symbols (quadratic and quartic) among its prime factors being given compatible values does not depend on the actual values. |
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