Previously (Weak) Homotopy Equivalences. An average function between sets, is neither surjective nor injective. We can however isolate the two “failure modes” if we insert a third set in between. We can, for instance, pick this set to be the subset of that is the image of under . We then define to be the […]| Bartosz Milewski's Programming Cafe
Previously: Fibrations and Cofibrations. In topology, we say that two shapes are the same if there is a homeomorphism– an invertible continuous map– between them. Continuity means that …| Bartosz Milewski's Programming Cafe
We are used to thinking of a mapping as either being invertible or not. It’s a yes or no question. A mapping between sets is invertible if it’s both injective and surjective. It means t…| Bartosz Milewski's Programming Cafe