Arithmetical properties of finite rings and algebras, and analytic number theory. III. Finite modules and algebras over Dedekind domains.
Let and be commutative rings with identity. An --biring is an -algebra together with a lift of the functor from -algebras to sets to a functor from -algebras to -algebras. An -plethory is a monoid object in the monoidal category, equipped with the composition product, of --birings. The polynomial ring is an initial object in the category of such structures. The -algebra has such a structure if is a domain such that the natural -algebra homomorphism is an isomorphism for...
Let be a non-maximal order in a finite algebraic number field with integral closure . Although is not a unique factorization domain, we obtain a positive integer and a family (called a Cale basis) of primary irreducible elements of such that has a unique factorization into elements of for each coprime with the conductor of . Moreover, this property holds for each nonzero when the natural map is bijective. This last condition is actually equivalent to several properties linked...
A method is presented making it possible to construct -groups with a strong theory of quasi-divisors of finite character and with some prescribed properties as subgroups of restricted Hahn groups , where are finitely atomic root systems. Some examples of these constructions are presented.
Soit un anneau de Dedekind, de corps des fractions , et soit une extension galoisienne de , dont le groupe de Galois est cyclique d’ordre premier. On note la clôture intégrale de dans . Il existe une unique décomposition du -module en somme directe de sous-modules indécomposables. On détermine cette décomposition lorsque est un corps local ou un corps de nombres. Le résultat dépend d’une part des caractères irréductibles de sur , d’autre part des nombres de ramification associés...
This note summarizes a presentation made at the Third International Meeting on Integer Valued Polynomials and Problems in Commutative Algebra. All the work behind it is joint with Scott T. Chapman, and will appear in [2]. Let represent the ring of polynomials with rational coefficients which are integer-valued at integers. We determine criteria for two such polynomials to have the same image set on .
Let be a Krull monoid with finite class group where every class contains some prime divisor. It is known that every set of lengths is an almost arithmetical multiprogression. We investigate which integers occur as differences of these progressions. In particular, we obtain upper bounds for the size of these differences. Then, we apply these results to show that, apart from one known exception, two elementary -groups have the same system of sets of lengths if and only if they are isomorphic.