منابع مشابه
Double Ore Extensions versus Iterated Ore Extensions
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...
متن کاملGalois Subrings of Ore Domains Are Ore Domains
If JR is a ring, and G is a group of automorphisms of R, then R denotes the subring of R consisting of elements of R left fixed by every element of G, and is called the Galois subring corresponding to G. In his paper, Groups acting on hereditary rings, G. M. Bergman has asked if every Galois subring of a right Ore domain corresponding to a finite group is itself right Ore. In this note we show ...
متن کاملFears over phosphorus supplies
" By 2030 demand for food will increase by 30 per cent and for water by 30 per cent, " said Guthrie. The report says that many countries were now using water unsustainably, by turning to desalination, which demands large amounts of energy, and by drawing on 'fossil' groundwater laid down millions of years ago. Libya, Algeria, and Saudi Arabia are taking vast quantities of fossil water from deep...
متن کاملFibers in Ore extensions
LetR be a finitely generated commutative algebra over an algebraically closed field k and let A = R[t;σ, δ] be the Ore extension with respect to an automorphism σ and a σ-derivation δ. We view A as the coordinate ring of an affine non-commutative space X. The inclusion R → A gives an affine map ξ : X → SpecR, and X is a non-commutative analogue of A 1 ×SpecR. We define the fiber Xp of ξ over a ...
متن کاملOre Polynomials in Sage
We present a Sage implementation of Ore algebras. The main features for the most common instances include basic arithmetic and actions; gcrd and lclm; D-finite closure properties; natural transformations between related algebras; guessing; desingularization; solvers for polynomials, rational functions and (generalized) power series. This paper is a tutorial on how to use the package.
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Geological Magazine
سال: 1907
ISSN: 0016-7568,1469-5081
DOI: 10.1017/s0016756800133850