carten.spad line 1 [edit on github]
GradedModule(R, E) denotes ``E-graded R-module'', i.e. collection of R-modules indexed by an abelian monoid E. An element g of G[s] for some specific s in E is said to be an element of G with degree s. Sums are defined in each module G[s] so two elements of G have a sum if they have the same degree. Morphisms can be defined and composed by degree to give the mathematical category of graded modules.
g*r is right module multiplication.
r*g is left module multiplication.
g+h is the sum of g and h in the module of elements of the same degree as g and h. Error: if g and h have different degrees.
-g is the additive inverse of g in the module of elements of the same grade as g.
g-h is the difference of g and h in the module of elements of the same degree as g and h. Error: if g and h have different degrees.
0 denotes the zero of degree 0.
degree(g) names the degree of g. The set of all elements of a given degree form an R-module.