My research is in analysis, but it moved to the area that requires algebraic topology. I have some working knowledge in that area, but I always feel that I am on a shaky ground and I need to go back and study algebraic topology again. However, that would also require refreshing my knowledge in algebra. My question is:

What is a good reference from which I could learn algebra necessary for studying algebraic topology at the level of Hatcher's Algebraic Topology plus Eilenberg-Steenrod's axioms (not included in Hatcher's book) plus spectral sequences (in unpublished notes of Hatcher).

I would love to find an elementary reference that would cover all necessary algebraic tools (including homological algebra) on no more than 100$\pm\varepsilon$ pages.

Algebracovers what you need, but it's more than 100 pages. Dummit and Foot is a nice undergraduate algebra book that covers essentially all you need, although it does not really develop homological algebra -- but you don't really need to know any homological algebra to study from Hatcher's book. Dummit and Foot is also over 100 pages. I imagine there is something that satisfies all your criteria. The undergraduate books all are a little longwinded compared to what you are looking for. $\endgroup$ – Ryan Budney Dec 29 '18 at 22:103more comments