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Explicit construction of integral bases of radical function fields

Qingquan Wu (2010)

Journal de Théorie des Nombres de Bordeaux

We give an explicit construction of an integral basis for a radical function field K = k ( t , ρ ) , where ρ n = D k [ t ] , under the assumptions [ K : k ( t ) ] = n and c h a r ( k ) n . The field discriminant of K is also computed. We explain why these questions are substantially easier than the corresponding ones in number fields. Some formulae for the P -signatures of a radical function field are also discussed in this paper.

Explicit upper bounds for |L(1,χ)| when χ(3) = 0

David J. Platt, Sumaia Saad Eddin (2013)

Colloquium Mathematicae

Let χ be a primitive Dirichlet character of conductor q and denote by L(z,χ) the associated L-series. We provide an explicit upper bound for |L(1,χ)| when 3 divides q.

Extended Euclidean Algorithm and CRT Algorithm

Hiroyuki Okazaki, Yosiki Aoki, Yasunari Shidama (2012)

Formalized Mathematics

In this article we formalize some number theoretical algorithms, Euclidean Algorithm and Extended Euclidean Algorithm [9]. Besides the a gcd b, Extended Euclidean Algorithm can calculate a pair of two integers (x, y) that holds ax + by = a gcd b. In addition, we formalize an algorithm that can compute a solution of the Chinese remainder theorem by using Extended Euclidean Algorithm. Our aim is to support the implementation of number theoretic tools. Our formalization of those algorithms is based...

Factor tables 1657–1817, with notes on the birth of number theory

Maarten Bullynck (2010)

Revue d'histoire des mathématiques

The history of the construction, organisation and publication of factor tables from 1657 to 1817, in itself a fascinating story, also touches upon many topics of general interest for the history of mathematics. The considerable labour involved in constructing and correcting these tables has pushed mathematicians and calculators to organise themselves in networks. Around 1660 J. Pell was the first to motivate others to calculate a large factor table, for which he saw many applications, from Diophantine...

Factoring and testing primes in small space

Viliam Geffert, Dana Pardubská (2013)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

We discuss how much space is sufficient to decide whether a unary given number n is a prime. We show that O(log log n) space is sufficient for a deterministic Turing machine, if it is equipped with an additional pebble movable along the input tape, and also for an alternating machine, if the space restriction applies only to its accepting computation subtrees. In other words, the language is a prime is in pebble–DSPACE(log log n) and also in accept–ASPACE(log log n). Moreover, if the given n is...

Factoring polynomials over global fields

Karim Belabas, Mark van Hoeij, Jürgen Klüners, Allan Steel (2009)

Journal de Théorie des Nombres de Bordeaux

We prove that van Hoeij’s original algorithm to factor univariate polynomials over the rationals runs in polynomial time, as well as natural variants. In particular, our approach also yields polynomial time complexity results for bivariate polynomials over a finite field.

Fast computation of class fields given their norm group

Loïc Grenié (2008)

Journal de Théorie des Nombres de Bordeaux

Let K be a number field containing, for some prime , the -th roots of unity. Let L be a Kummer extension of degree of K characterized by its modulus 𝔪 and its norm group. Let K 𝔪 be the compositum of degree extensions of K of conductor dividing 𝔪 . Using the vector-space structure of Gal ( K 𝔪 / K ) , we suggest a modification of the rnfkummer function of PARI/GP which brings the complexity of the computation of an equation of L over K from exponential to linear.

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