I know what a chain homotopy is, but can anyone tell me what a natural chain homotopy is?
I know this means that it must arise from a functor but what category is a natural chain homotopy a morphism in?
I understand what a natural chain map is, since those are morphisms in the category of chain complexes.
Thanks for any help !
well my book (Dold) has a diagram and says F0,F1 and s satisfy the naturality diagram, (Where F0,F1 are natural chain maps and s is a natural chain homotopy)
but I didn't understand this since F,G are chain maps, and s is not a chain map. Also chain homotopies go between abelian groups, not topological spaces. Thanks for your answer, I will try to upload a picture so you can see what im on about