Counting the Restricted Gaussian Partitions of a Finite Vector Space
Fusun Akman and Papa A. Sissokho
4520 Mathematics Department
Illinois State University
Normal, IL 61790-4520
USA
Abstract:
A subspace partition Π of a finite vector space V =
V(n,q) of dimension n over GF(q) is
a collection of subspaces of V such that their union is
V, and the intersection of any two subspaces in Π is the zero
vector. The multiset TΠ of dimensions of
subspaces in Π is called the type of Π, or, a Gaussian partition
of V. Previously, we showed that subspace partitions of V
and their types are natural, combinatorial q-analogues of the
set partitions of {1,...,n} and integer partitions of n
respectively. In this paper, we connect all four types of partitions
through the concept of "basic" set, subspace, and Gaussian
partitions, corresponding to the integer partitions of n. In
particular, we combine Beutelspacher's classic construction of
subspace partitions with some additional conditions to derive a special
subset 𝓖 of Gaussian partitions of V. We then show that
the cardinality of 𝓖 is a rational polynomial
R(q) in q, with R(1) = p(n),
where p is the integer partition function.
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Received
September 5 2014;
revised versions received December 16 2014; July 15 2015.
Published in Journal of Integer Sequences, July 16 2015.
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