Decomposition matrix: Difference between revisions

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In [[mathematics]], and in particular [[modular representation theory]], a '''decomposition matrix''' is a [[matrix (mathematics)|matrix]] that results from writing the irreducible [[ordinary character]]s in terms of the irreducible [[modular character]]s, where the entries of the two sets of characters are taken to be over all [[conjugacy classesclass]]es of elements of [[order (group theory)|order]] [[coprime]] to the [[characteristic (algebra)|characteristic]] of the [[field (mathematics)|field]]. All such entries in the matrix are non-negative integers[[integer]]s. The decomposition matrix, multiplied by its [[transpose]], forms the [[Cartan matrix]], listing the composition factors of the [[projective module]]s.

==References==