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Extensions of Büchi's problem: Questions of decidability for addition and kth powers

Thanases Pheidas, Xavier Vidaux (2005)

Fundamenta Mathematicae

We generalize a question of Büchi: Let R be an integral domain, C a subring and k ≥ 2 an integer. Is there an algorithm to decide the solvability in R of any given system of polynomial equations, each of which is linear in the kth powers of the unknowns, with coefficients in C? We state a number-theoretical problem, depending on k, a positive answer to which would imply a negative answer to the question for R = C = ℤ. We reduce a negative answer for k = 2 and for...

Extensions of the Bloch–Pólya theorem on the number of real zeros of polynomials

Tamás Erdélyi (2008)

Journal de Théorie des Nombres de Bordeaux

We prove that there are absolute constants c 1 > 0 and c 2 > 0 such that for every { a 0 , a 1 , ... , a n } [ 1 , M ] , 1 M exp ( c 1 n 1 / 4 ) , there are b 0 , b 1 , ... , b n { - 1 , 0 , 1 } such that P ( z ) = j = 0 n b j a j z j has at least c 2 n 1 / 4 distinct sign changes in ( 0 , 1 ) . This improves and extends earlier results of Bloch and Pólya.

Extensions of the Cugiani-Mahler theorem

Yann Bugeaud (2007)

Annali della Scuola Normale Superiore di Pisa - Classe di Scienze

In 1955, Roth established that if ξ is an irrational number such that there are a positive real number ε and infinitely many rational numbers p / q with q 1 and | ξ - p / q | < q - 2 - ε , then ξ is transcendental. A few years later, Cugiani obtained the same conclusion with ε replaced by a function q ε ( q ) that decreases very slowly to zero, provided that the sequence of rational solutions to | ξ - p / q | < q - 2 - ε ( q ) is sufficiently dense, in a suitable sense. We give an alternative, and much simpler, proof of Cugiani’s Theorem and extend it to simultaneous...

Extensions of Three Theorems of Nagell

A. Schinzel (2013)

Bulletin of the Polish Academy of Sciences. Mathematics

Three theorems of Nagell of 1923 concerning integer values of certain sums of fractions are extended.

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