
arXiv: 1005.5222
A notion of degeneration of elements in groups is introduced. It is used to parametrize the orbits in a finite abelian group under its full automorphism group by a finite distributive lattice. A pictorial description of this lattice leads to an intuitive self-contained exposition of some of the basic facts concerning these orbits, including their enumeration. Given a partition $λ$, the lattice parametrizing orbits in a finite abelian p-group of type $λ$ is found to be independent of p. The order of the orbit corresponding to each parameter, which turns out to be a polynomial in p, is calculated. The description of orbits is extended to subquotients by certain characteristic subgroups. Each such characteristic subquotient is shown to have a unique maximal orbit.
14 pages, 5 figures
Finite abelian groups, partial orders, characteristic subgroups, automorphisms, Mathematics - Number Theory, Automorphisms, homomorphisms, endomorphisms, etc. for abelian groups, 20K01, 05A15, Exact enumeration problems, generating functions, orbits, Orbits, Group Theory (math.GR), Theoretical Computer Science, Computational Theory and Mathematics, Partial order, FOS: Mathematics, Discrete Mathematics and Combinatorics, Mathematics - Combinatorics, Combinatorics (math.CO), Number Theory (math.NT), finite Abelian groups, Mathematics - Group Theory, Arithmetic and combinatorial problems involving abstract finite groups
Finite abelian groups, partial orders, characteristic subgroups, automorphisms, Mathematics - Number Theory, Automorphisms, homomorphisms, endomorphisms, etc. for abelian groups, 20K01, 05A15, Exact enumeration problems, generating functions, orbits, Orbits, Group Theory (math.GR), Theoretical Computer Science, Computational Theory and Mathematics, Partial order, FOS: Mathematics, Discrete Mathematics and Combinatorics, Mathematics - Combinatorics, Combinatorics (math.CO), Number Theory (math.NT), finite Abelian groups, Mathematics - Group Theory, Arithmetic and combinatorial problems involving abstract finite groups
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