# Semisimple Algebras¶

class sage.categories.semisimple_algebras.SemisimpleAlgebras(base, name=None)

The category of semisimple algebras over a given base ring.

EXAMPLES:

sage: from sage.categories.semisimple_algebras import SemisimpleAlgebras
sage: C = SemisimpleAlgebras(QQ); C
Category of semisimple algebras over Rational Field


This category is best constructed as:

sage: D = Algebras(QQ).Semisimple(); D
Category of semisimple algebras over Rational Field
sage: D is C
True

sage: C.super_categories()
[Category of algebras over Rational Field]


Typically, finite group algebras are semisimple:

sage: DihedralGroup(5).algebra(QQ) in SemisimpleAlgebras
True


Unless the characteristic of the field divides the order of the group:

sage: DihedralGroup(5).algebra(IntegerModRing(5)) in SemisimpleAlgebras
False

sage: DihedralGroup(5).algebra(IntegerModRing(7)) in SemisimpleAlgebras
True

class FiniteDimensional(base_category)
WithBasis
class ParentMethods
radical_basis(**keywords)

Return a basis of the Jacobson radical of this algebra.

• keywords – for compatibility; ignored.

OUTPUT: the empty list since this algebra is semisimple.

EXAMPLES:

sage: A = SymmetricGroup(4).algebra(QQ)

super_categories()
sage: Algebras(QQ).Semisimple().super_categories()