2,245 research outputs found
Sequences of irreducible polynomials without prescribed coefficients over odd prime fields
In this paper we construct infinite sequences of monic irreducible
polynomials with coefficients in odd prime fields by means of a transformation
introduced by Cohen in 1992. We make no assumptions on the coefficients of the
first polynomial of the sequence, which belongs to \F_p [x], for some
odd prime , and has positive degree . If for
some odd integer and non-negative integer , then, after an initial
segment with , the degree of the polynomial
is twice the degree of for any .Comment: 10 pages. Fixed a typo in the reference
Using approximate roots for irreducibility and equi-singularity issues in K[[x]][y]
We provide an irreducibility test in the ring K[[x]][y] whose complexity is
quasi-linear with respect to the valuation of the discriminant, assuming the
input polynomial F square-free and K a perfect field of characteristic zero or
greater than deg(F). The algorithm uses the theory of approximate roots and may
be seen as a generalization of Abhyankhar's irreducibility criterion to the
case of non algebraically closed residue fields. More generally, we show that
we can test within the same complexity if a polynomial is pseudo-irreducible, a
larger class of polynomials containing irreducible ones. If is
pseudo-irreducible, the algorithm computes also the valuation of the
discriminant and the equisingularity types of the germs of plane curve defined
by F along the fiber x=0.Comment: 51 pages. Title modified. Slight modifications in Definition 5 and
Proposition 1
The density of primes in orbits of z^d + c
Given a polynomial f(z) = z^d + c over a global field K and a_0 in K, we
study the density of prime ideals of K dividing at least one element of the
orbit of a_0 under f. The density of such sets for linear polynomials has
attracted much study, and the second author has examined several families of
quadratic polynomials, but little is known in the higher-degree case. We show
that for many choices of d and c this density is zero for all a_0, assuming K
contains a primitive dth root of unity. The proof relies on several new
results, including some ensuring the number of irreducible factors of the nth
iterate of f remains bounded as n grows, and others on the ramification above
certain primes in iterated extensions. Together these allow for nearly complete
information when K is a global function field or when K=Q(zeta_d).Comment: 27 page
L-functions with large analytic rank and abelian varieties with large algebraic rank over function fields
The goal of this paper is to explain how a simple but apparently new fact of
linear algebra together with the cohomological interpretation of L-functions
allows one to produce many examples of L-functions over function fields
vanishing to high order at the center point of their functional equation. The
main application is that for every prime p and every integer g>0 there are
absolutely simple abelian varieties of dimension g over Fp(t) for which the BSD
conjecture holds and which have arbitrarily large rank.Comment: To appear in Inventiones Mathematica
On the discrete logarithm problem in finite fields of fixed characteristic
For a prime power, the discrete logarithm problem (DLP) in
consists in finding, for any
and , an integer such that . We present
an algorithm for computing discrete logarithms with which we prove that for
each prime there exist infinitely many explicit extension fields
in which the DLP can be solved in expected quasi-polynomial
time. Furthermore, subject to a conjecture on the existence of irreducible
polynomials of a certain form, the algorithm solves the DLP in all extensions
in expected quasi-polynomial time.Comment: 15 pages, 2 figures. To appear in Transactions of the AM
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