Affine complete Abelian groups
β Scribed by K. Kaarli
- Publisher
- John Wiley and Sons
- Year
- 1982
- Tongue
- English
- Weight
- 258 KB
- Volume
- 107
- Category
- Article
- ISSN
- 0025-584X
No coin nor oath required. For personal study only.
β¦ Synopsis
In this paper the classification of ABELian groups in terms of affine completeness initiated by LAUSH and NOBAUER in [2] and continued by N~BAUER in [3] and [4] is completed.
1. Preliminaries.
The word "group" will mean, throughout the paper, "ABELian group". If X is a subset of a group A. then (X) denotes the subgroup generated by X. Definition 1.1. Let A 1% a group and let X, F be subsets in A. Y SX. A mapping g~ : for any elements ui, wi< I' (i = I , . . . , n). Definition 1.2. Let A, X, Y be as in the definition 1.1. A mapping tp : X" -+A is called polynomial, if there exist integers kl, . . . , &* and an element caEA such that -A is cdled compatible on Y, if q(a,. . . . , W")--qJ(@I.. . . , w")E(u,-v~. -. .. a * -. , ! Q(Y~, . . a , ~~) = k l ~l + .
. . +knyn+a for any elements yi, . , . , yne 1'. \Ye denote the set of all mappings cp : X"-A which are compatible on X (polynomial on X ) by Pz(A) (PR,(A)). If X = A . then we use notations P ( A ) and P ( A ) instead of PA(A) and P",(A) correspondingly. Obviously, P&4) ZC'&(A) for any subset X and. in particular.
P ( A ) g C " ( A ) .
Now we give the main definition of this paper.
π SIMILAR VOLUMES
If A is a fixed abelian group with endomorphism ring E, then for any group G, Ε½ . Ε½ . let G\* s Hom G, A and for any E-module M, let M\* s Hom M, A . The E evaluation map : G Βͺ G\*\* is defined in the usual way and G is A-reflexive if G is an isomorphism. This is strongly related to the question of
In this paper we study the Weyl groups of reduced extended affine root systems, the root systems of extended affine Lie algebras. We start by describing the extended affine Weyl group as a semidirect product of a finite Weyl group and a Heisenberg-like normal subgroup. This provides a unique express
## Abstract We prove that, with the single exception of the 2βgroup __C__, the Cayley table of each Abelian group appears in a face 2βcolorable triangular embedding of a complete regular tripartite graph in an orientable surface. Β© 2009 Wiley Periodicals, Inc. J Combin Designs 18: 71β83, 2010
d h . I & k und Brundloqcn d . Math Bd. 21, s. 303-305 (1975) WEAK COMPLETENESS AND ABELIAN SEMIGROUPS by T. C. WESSELKAMPER Blacksburg, Virginia (U.S.A.) Let k be a natural number ( k 2 3 ) and let E ( k ) = (0, 1, . . . , k -1). Let moreover c' = {ha I ha: E ( k ) + {a}}, the set of constant func