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Galois structure of ideals in wildly ramified abelian p -extensions of a p -adic field, and some applications

Nigel P. Byott (1997)

Journal de théorie des nombres de Bordeaux

Let K be a finite extension of p with ramification index e , and let L / K be a finite abelian p -extension with Galois group Γ and ramification index p n . We give a criterion in terms of the ramification numbers t i for a fractional ideal 𝔓 h of the valuation ring S of L not to be free over its associated order 𝔄 ( K Γ ; 𝔓 h ) . In particular, if t n - [ t n / p ] < p n - 1 e then the inverse different can be free over its associated order only when t i - 1 (mod p n ) for all i . We give three consequences of this. Firstly, if 𝔄 ( K Γ ; S ) is a Hopf order and S is 𝔄 ( K Γ ; S ) -Galois...

Galois theory and torsion points on curves

Matthew H. Baker, Kenneth A. Ribet (2003)

Journal de théorie des nombres de Bordeaux

In this paper, we survey some Galois-theoretic techniques for studying torsion points on curves. In particular, we give new proofs of some results of A. Tamagawa and the present authors for studying torsion points on curves with “ordinary good” or “ordinary semistable” reduction at a given prime. We also give new proofs of : (1) the Manin-Mumford conjecture : there are only finitely many torsion points lying on a curve of genus at least 2 embedded in its jacobian by an Albanese map; and (2) the...

Galois towers over non-prime finite fields

Alp Bassa, Peter Beelen, Arnaldo Garcia, Henning Stichtenoth (2014)

Acta Arithmetica

We construct Galois towers with good asymptotic properties over any non-prime finite field ; that is, we construct sequences of function fields = (N₁ ⊂ N₂ ⊂ ⋯) over of increasing genus, such that all the extensions N i / N 1 are Galois extensions and the number of rational places of these function fields grows linearly with the genus. The limits of the towers satisfy the same lower bounds as the best currently known lower bounds for the Ihara constant for non-prime finite fields. Towers with these properties...

Gaps between consecutive divisors of factorials

Daniel Berend, J. E. Harmse (1993)

Annales de l'institut Fourier

The set of all divisors of n ! , ordered according to increasing magnitude, is considered, and an upper bound on the gaps between consecutive ones is obtained. We are especially interested in the divisors nearest n ! and obtain a lower bound on their distance.

Gaps between primes in Beatty sequences

Roger C. Baker, Liangyi Zhao (2016)

Acta Arithmetica

We study the gaps between primes in Beatty sequences following the methods in the recent breakthrough by Maynard (2015).

Gaps between zeros of the derivative of the Riemann ξ -function

Hung Manh Bui (2010)

Journal de Théorie des Nombres de Bordeaux

Assuming the Riemann hypothesis, we investigate the distribution of gaps between the zeros of ξ ( s ) . We prove that a positive proportion of gaps are less than 0 . 796 times the average spacing and, in the other direction, a positive proportion of gaps are greater than 1 . 18 times the average spacing. We also exhibit the existence of infinitely many normalized gaps smaller (larger) than 0 . 7203 ( 1 . 5 , respectively).

Currently displaying 41 – 60 of 370