Displaying similar documents to “Markoff numbers and ambiguous classes”

On a theorem of Mestre and Schoof

John E. Cremona, Andrew V. Sutherland (2010)

Journal de Théorie des Nombres de Bordeaux

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A well known theorem of Mestre and Schoof implies that the order of an elliptic curve E over a prime field 𝔽 q can be uniquely determined by computing the orders of a few points on E and its quadratic twist, provided that q > 229 . We extend this result to all finite fields with q > 49 , and all prime fields with q > 29 .

Rational approximations to 2 3 and other algebraic numbers revisited

Paul M. Voutier (2007)

Journal de Théorie des Nombres de Bordeaux

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In this paper, we establish improved effective irrationality measures for certain numbers of the form n 3 , using approximations obtained from hypergeometric functions. These results are very close to the best possible using this method. We are able to obtain these results by determining very precise arithmetic information about the denominators of the coefficients of these hypergeometric functions. Improved bounds for the Chebyshev functions in arithmetic progressions θ ( k , l ; x ) and...

Weber’s class number problem in the cyclotomic ℤ 2 -extension of ℚ , II

Takashi Fukuda, Keiichi Komatsu (2010)

Journal de Théorie des Nombres de Bordeaux

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Let h n denote the class number of n -th layer of the cyclotomic ℤ 2 -extension of ℚ . Weber proved that h n ( n ≥ 1 ) is odd and Horie proved that h n ( n ≥ 1 ) is not divisible by a prime number ℓ satisfying ℓ ≡ 3 , 5 ( mod 8 ) . In a previous paper, the authors showed that h n ( n ≥ 1 ) is not divisible by a prime number ℓ less than 10 7 . In this paper, by investigating properties of a special unit more precisely, we show that h n ( n ≥ 1 ) is not divisible by a prime number ℓ less than 1 . 2 · 10 8 . Our argument also leads to the conclusion that h n ( n ≥ 1 ) is not divisible by...