21,759 research outputs found
-Torsion Points In Finite Abelian Groups And Combinatorial Identities
The main aim of this article is to compute all the moments of the number of
-torsion elements in some type of nite abelian groups. The averages
involved in these moments are those de ned for the Cohen-Lenstra heuristics for
class groups and their adaptation for Tate-Shafarevich groups. In particular,
we prove that the heuristic model for Tate-Shafarevich groups is compatible
with the recent conjecture of Poonen and Rains about the moments of the orders
of -Selmer groups of elliptic curves. For our purpose, we are led to de ne
certain polynomials indexed by integer partitions and to study them in a
combinatorial way. Moreover, from our probabilistic model, we derive
combinatorial identities, some of which appearing to be new, the others being
related to the theory of symmetric functions. In some sense, our method
therefore gives for these identities a somehow natural algebraic context.Comment: 24 page
van Douwen's problems related to the Bohr topology
We comment van Douwen's problems on the Bohr topology of the abelian groups
raised in his paper (The maximal totally bounded group topology on G and the
biggest minimal G-space for Abelian groups G) as well as the steps in the
solution of some of them. New solutions to two of the resolved problems are
also given.Comment: 14 page
On a conjecture of Gluck
Let and respectively denote the Fitting subgroup and the
largest degree of an irreducible complex character of a finite group . A
well-known conjecture of D. Gluck claims that if is solvable then
. We confirm this conjecture in the case where
is coprime to 6. We also extend the problem to arbitrary finite groups and
prove several results showing that the largest irreducible character degree of
a finite group strongly controls the group structure.Comment: 16 page
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