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On subfields of k ( x )

Victor Alexandru, Nicolae Popescu (1986)

Rendiconti del Seminario Matematico della Università di Padova

On the compositum of all degree d extensions of a number field

Itamar Gal, Robert Grizzard (2014)

Journal de Théorie des Nombres de Bordeaux

We study the compositum k [ d ] of all degree d extensions of a number field k in a fixed algebraic closure. We show k [ d ] contains all subextensions of degree less than d if and only if d 4 . We prove that for d > 2 there is no bound c = c ( d ) on the degree of elements required to generate finite subextensions of k [ d ] / k . Restricting to Galois subextensions, we prove such a bound does not exist under certain conditions on divisors of d , but that one can take c = d when d is prime. This question was inspired by work of Bombieri and...

On the dimension of the space of ℝ-places of certain rational function fields

Taras Banakh, Yaroslav Kholyavka, Oles Potyatynyk, Michał Machura, Katarzyna Kuhlmann (2014)

Open Mathematics

We prove that for every n ∈ ℕ the space M(K(x 1, …, x n) of ℝ-places of the field K(x 1, …, x n) of rational functions of n variables with coefficients in a totally Archimedean field K has the topological covering dimension dimM(K(x 1, …, x n)) ≤ n. For n = 2 the space M(K(x 1, x 2)) has covering and integral dimensions dimM(K(x 1, x 2)) = dimℤ M(K(x 1, x 2)) = 2 and the cohomological dimension dimG M(K(x 1, x 2)) = 1 for any Abelian 2-divisible coefficient group G.

On the distribution of the roots of polynomial z k - z k - 1 - - z - 1

Carlos A. Gómez, Florian Luca (2021)

Commentationes Mathematicae Universitatis Carolinae

We consider the polynomial f k ( z ) = z k - z k - 1 - - z - 1 for k 2 which arises as the characteristic polynomial of the k -generalized Fibonacci sequence. In this short paper, we give estimates for the absolute values of the roots of f k ( z ) which lie inside the unit disk.

On the Galois group of generalized Laguerre polynomials

Farshid Hajir (2005)

Journal de Théorie des Nombres de Bordeaux

Using the theory of Newton Polygons, we formulate a simple criterion for the Galois group of a polynomial to be “large.” For a fixed α - < 0 , Filaseta and Lam have shown that the n th degree Generalized Laguerre Polynomial L n ( α ) ( x ) = j = 0 n n + α n - j ( - x ) j / j ! is irreducible for all large enough n . We use our criterion to show that, under these conditions, the Galois group of L n ( α ) ( x ) is either the alternating or symmetric group on n letters, generalizing results of Schur for α = 0 , 1 , ± 1 2 , - 1 - n .

Currently displaying 261 – 280 of 459