Iterated extensions
نویسندگان
چکیده
منابع مشابه
Finitely Ramified Iterated Extensions
Let p be a prime number, K a number field, and S a finite set of places of K. Let KS be the compositum of all extensions of K (in a fixed algebraic closure K) which are unramified outside S, and put GK,S = Gal(KS/K) for its Galois group. These arithmetic fundamental groups play a very important role in number theory. Algebraic geometry provides the most fruitful known source of information conc...
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Motivated by the construction of new examples of Artin-Schelter regular algebras of global dimension four, J.J.Zhang and J.Zhang (2008) introduced an algebra extension AP [y1, y2;σ, δ, τ ] of A, which they called a double Ore extension. This construction seems to be similar to that of a two-step iterated Ore extension over A. The aim of this paper is to describe those double Ore extensions whic...
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Let k be an algebraically closed field, let R be an associative kalgebra, and let F = {Mα : α ∈ I} be a family of orthogonal points in Mod(R) such that EndR(Mα) ∼= k for all α ∈ I. Then Mod(F), the minimal full subcategory of Mod(R) which contains F and is closed under extensions, is a full exact Abelian sub-category of Mod(R) and a length category in the sense of Gabriel [8]. In this paper, we...
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Let F be a characteristic zero differential field with an algebraically closed field of constants C, E ⊃ F be a no new constant extension by antiderivatives of F and let y1, · · · yn be antiderivatives of E. The antiderivatives y1, · · · , yn of E are called J-I-E antiderivatives if y′i ∈ E satisfies certain conditions. We will discuss a new proof for the KolchinOstrowski theorem and generalize...
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Let K be a number field, t a parameter, F = K(t), and ϕ(x) ∈ K[x] a polynomial of degree d ≥ 2. The polynomial Φ n (x, t) = ϕ • n (x)−t ∈ F [x], where ϕ • n = ϕ • ϕ • · · · • ϕ is the n-fold iterate of ϕ, is absolutely irreducible over F ; we compute a recursion for its discriminant. Let F ϕ be the field obtained by adjoining to F all roots (in a fixed F) of Φ n (x, t) for all n ≥ 1; its Galois...
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ژورنال
عنوان ژورنال: Ergodic Theory and Dynamical Systems
سال: 1982
ISSN: 0143-3857,1469-4417
DOI: 10.1017/s0143385700009536