ScalingStacks

Definition 8 A homomorphism of graded $A$-modules $M$ and $N$ is a grading-preserving homomorphism of abelian groups $f:M\to N$ that intertwines the action of $X$ and $c$ in $M$ and $N$:

$$Xf=fX,\hskip 36.135ptcf=fc.$$

(186)