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Computing all monogeneous mixed dihedral quartic extensions of a quadratic field

István Gaál, Gábor Nyul (2001)

Journal de théorie des nombres de Bordeaux

Let M be a given real quadratic field. We give a fast algorithm for determining all dihedral quartic fields K with mixed signature having power integral bases and containing M as a subfield. We also determine all generators of power integral bases in K . Our algorithm combines a recent result of Kable [9] with the algorithm of Gaál, Pethö and Pohst [6], [7]. To illustrate the method we performed computations for M = ( 2 ) , ( 3 ) , ( 5 ) .

Congruent numbers over real number fields

Tomasz Jędrzejak (2012)

Colloquium Mathematicae

It is classical that a natural number n is congruent iff the rank of ℚ -points on Eₙ: y² = x³-n²x is positive. In this paper, following Tada (2001), we consider generalised congruent numbers. We extend the above classical criterion to several infinite families of real number fields.

Congruent numbers with higher exponents

Florian Luca, László Szalay (2006)

Acta Mathematica Universitatis Ostraviensis

This paper investigates the system of equations x 2 + a y m = z 1 2 , x 2 - a y m = z 2 2 in positive integers x , y , z 1 , z 2 , where a and m are positive integers with m 3 . In case of m = 2 we would obtain the classical problem of congruent numbers. We provide a procedure to solve the simultaneous equations above for a class of the coefficient a with the condition gcd ( x , z 1 ) = gcd ( x , z 2 ) = gcd ( z 1 , z 2 ) = 1 . Further, under same condition, we even prove a finiteness theorem for arbitrary nonzero a .

Contre-exemples au principe de Hasse pour certains tores coflasques

Régis de la Bretèche, Tim Browning (2014)

Journal de Théorie des Nombres de Bordeaux

Nous étudions le comportement asymptotique du nombre de variétés dans une certaine classe ne satisfaisant pas le principe de Hasse. Cette étude repose sur des résultats récemment obtenus par Colliot-Thélène [3].

Contre-exemples au principe de Hasse pour les courbes de Fermat

Alain Kraus (2016)

Acta Arithmetica

Let p be an odd prime number. In this paper, we are concerned with the behaviour of Fermat curves defined over ℚ, given by equations a x p + b y p + c z p = 0 , with respect to the local-global Hasse principle. It is conjectured that there exist infinitely many Fermat curves of exponent p which are counterexamples to the Hasse principle. This is a consequence of the abc-conjecture if p ≥ 5. Using a cyclotomic approach due to H. Cohen and Chebotarev’s density theorem, we obtain a partial result towards this conjecture, by...

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