Overview

This section of the Handbook describes the Magma facilities for linear algebra and module theory. Since this topic is absolutely fundamental for much of algebra, it is important that the reader understand how linear algebra is presented in Magma. The structures covered under this heading include:

(i)
Vector spaces;
(ii)
Inner product spaces;
(iii)
Modules defined over any ring or algebra
(iv)
R[G]-modules, where R is a ring and G is a group;
(v)
Linear transformations and R-module homomorphisms.

Although vector spaces are, of course, subsumed under general modules, we present a separate treatment of them, firstly because of their importance and secondly because their theory is somewhat cleaner than that of a general module. Magma users who are unfamiliar with the language of module theory will find a self-contained treatment of the vector space machinery in Chapter VECTOR SPACES.

In the Magma universe, rectangular matrices are regarded as forming a module (actually a bimodule). We shall regard a rectangular matrix as the concrete realization of a linear transformation or R-module homomorphism. Thus, an m x n matrix over a ring R is considered to be an element of the module HomR(M, N). Reflecting the dual nature of matrices, the HomR(M, N) operations include the standard module-theoretic operations as well as operations that interpret an element of HomR(M, N) as a homomorphism.

V2.28, 13 July 2023