projective object造句

例句与造句

1. Free functors are projective objects in that category.
2. Furthermore, assuming the axiom of choice, the free abelian groups are precisely the projective objects in the category of abelian groups.
3. At each stage of the induction, the properties of projective objects are used to define maps in a projective resolution of A.
4. It's difficult to find projective object in a sentence. 用projective object造句挺难的