A cotensor product A HP of an H-Hopf Galois extension A and a C-coalgebra Galois extension P , such that P is an (H,C)-bicomodule, is analyzed. Conditions are stated, when A HP is a C-coalgebra Galois extension and when there exists a strong connection on A HP . Two examples are given, in both, A and P are Matsumoto spheres, and H = C = C(U(1)).

Let K be a cyclic Galois extension of degree p over a field F containing a primitive pth root of unity. We consider Galois embedding problems involving Galois groups with common quotient Gal(K/F ) such that corresponding normal subgroups are indecomposable Fp[Gal(K/F )]modules. For these embedding problems we prove conditions on solvability, formulas for explicit construction, and results on au...

Let K be a field of characteristic not p (an odd prime), containing a primitive p-th root of unity ζ, and let L = K[z] with x n − a the minimal polynomial of z over K: thus L|K is a Kummer extension, with cyclic Galois group G = 〈σ〉 acting on L via σ(z) = ζz. T. Kohl, 1998, showed that L|K has pn−1 Hopf Galois structures. In this paper we describe these Hopf Galois structures.

Let K be a cyclic Galois extension of degree p over a field F containing a primitive pth root of unity. We consider Galois embedding problems involving Galois groups with common quotient Gal(K/F ) such that corresponding normal subgroups are indecomposable Fp[Gal(K/F )]modules. For these embedding problems we prove conditions on solvability, formulas for explicit construction, and results on au...

We discuss some new properties of the natural Galois connection among set relation algebras, permutation groups, and first order logic. In particular, we exhibit infinitely many permutational relation algebras without a Galois closed representation, and we also show that every relation algebra on a set with at most six elements is Galois closed and essentially unique. Thus, we obtain the surpri...

The category of finite dimensional modules for the proalgebraic differential Galois group of the differential Galois theoretic closure of a differential field F is equivalent to the category of finite dimensional F spaces with an endomorphism extending the derivation of F . This paper presents an expository proof of this fact modeled on a similar equivalence from polynomial Galois theory, whose...

We construct and study two series of curves whose Jacobians admit complex multiplication. The curves arise as quotients of Galois coverings of the projective line with Galois group metacyclic groups Gq,3 of order 3q with q ≡ 1 mod 3 an odd prime, and Gm of order 2 . The complex multiplications arise as quotients of double coset algebras of the Galois groups of these coverings. We work out the C...

The aim of this paper is to introduce the quantum analogues of torsors for a compact quantum group and to investigate their relations with representation theory. Let A be a Hopf algebra over a field k. A theorem of Ulbrich asserts that there is an equivalence of categories between neutral fibre functors on the category of finitedimensional A-comodules and A-Galois extensions of k. We give the c...

In this work we give a characterization of Galois Linear Complementary Dual codes and Galois-invariant over mixed alphabets finite chain rings, which leads to the study Gray image F p [ θ ] -linear codes, where ∈ { 2 ; 3 } ≠ = 0 that provides LCD .

This is a copy of our March 2004 preprint where we attempted to: “prove Serre’s conjecture for the case of Galois representations with Serre’s weight 2 and level 1. We do this by combining the potential modularity results of Taylor and lowering the level for Hilbert modular forms with a Galois descent argument and the non-existence of certain p-adic conductor 1 Galois representations”. Since a ...