Homomorphisms

Magma has the capability of creating homomorphisms of basic algebras. A homomorphism of a basic algebra has the type Map. The matrix of the homomorphism φ is accessed by entering Matrix(phi). The kernel of a homomorphism is returned as a subspace of the vector space of the domain of the algebra. This is a two-sided ideal. There is no special type for ideals. They are subspaces of the underlying vector space of the algebra. They can be generated from any given set of elements of the algebra

The image of a homomorphism is returned as a basic algebra, together with the embedding homomorphism.

A homomorphism from a basic algebra A to a basic algebra B is normally created from a matrix having dimension of A rows and dimension of B columns. Note that Magma does not automatically check to see if the created map is an algebra homomorphism.

hom<A -> B | S> : AlgBas, AlgBas, ModMatFldElt -> Map
The algebra homomorphism from basic algebra A to basic algebra B, whose matrix is the matrix S. Given a map φ, a homomorphism of basic algebra, the matrix of that map is recalled with the command Matrix(phi).
Kernel(phi) : Map -> ModTupFld
The kernel of the map φ.
Image(phi) : Map -> AlgBas, Map
The image of the homomorphism φ together with the embedding homomorphism of the image into the codomain of φ.
IsAlgebraHomomorphism(A, B, psi) : AlgBas, AlgBas, Mtrx -> Bool
Return true if the matrix ψ represents a homomorphism from basic algebra A to basic algebra B.
X * Y : Map, Map -> Map
The composition of the maps X and Y.
IsAlgebraHomomorphism(A, B, psi) : AlgBas, AlgBas, Map -> Bool
IsAlgebraHomomorphism(A, B, psi) : AlgBasGrpP, AlgBasGrpP, Map -> Bool
IsAlgebraHomomorphism(A, B, psi) : AlgBasGrpP, AlgBas, Map -> Bool
IsAlgebraHomomorphism(A, B, psi) : AlgBas, AlgBasGrpP, Map -> Bool
Returns true, if the map ψ is a homomorphism of basic algebras
IsAlgebraHomomorphism(psi): Map -> Bool
Returns true if the map ψ is a homomorphism of basic algebras.
V2.28, 13 July 2023