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An abelian function is a meromorphic function on an abelian variety, which may be regarded therefore as a periodic function of n complex variables, having 2n independent periods; equivalently, it is a function in the function field of an abelian variety.
In mathematics, in the field of abstract algebra, the structure theorem for finitely generated modules over a principal ideal domain is a generalization of the fundamental theorem of finitely generated abelian groups and roughly states that finitely generated modules over a principal ideal domain (PID) can be uniquely decomposed in much the same way that integers have a prime factorization.
For abelian groups G and H which are written additively, the direct product of G and H is also called a direct sum (Mac Lane & Birkhoff 1999, §V.6). Thus the Cartesian product G × H is equipped with the structure of an abelian group by defining the operations componentwise: (g 1, h 1) + (g 2, h 2) = (g 1 + g 2, h 1 + h 2) for g 1, g 2 in G ...
A topological vector space (TVS) , such as a Banach space, is said to be a topological direct sum of two vector subspaces and if the addition map (,) + is an isomorphism of topological vector spaces (meaning that this linear map is a bijective homeomorphism) in which case and are said to be topological complements in .
To qualify as an abelian group, the set and operation, (,), must satisfy four requirements known as the abelian group axioms (some authors include in the axioms some properties that belong to the definition of an operation: namely that the operation is defined for any ordered pair of elements of A, that the result is well-defined, and that the ...
Every elementary abelian p-group is a vector space over the prime field with p elements, and conversely every such vector space is an elementary abelian group. By the classification of finitely generated abelian groups , or by the fact that every vector space has a basis , every finite elementary abelian group must be of the form ( Z / p Z ) n ...
An abelian group A is torsion-free if and only if it is flat as a Z-module, which means that whenever C is a subgroup of some abelian group B, then the natural map from the tensor product C ⊗ A to B ⊗ A is injective. Tensoring an abelian group A with Q (or any divisible group) kills torsion. That is, if T is a torsion group then T ⊗ Q = 0.
If A is torsion-free then the canonical map A → A ⊗ Q is injective and the rank of A is the minimum dimension of Q-vector space containing A as an abelian subgroup. In particular, any intermediate group Z n < A < Q n has rank n. Abelian groups of rank 0 are exactly the periodic abelian groups. The group Q of rational numbers has rank 1.