Today we prove the "baby uniqueness theorem" from last time. We then introduce free chain complexes, and prove a weak version of the so-called Comparison Theorem in homological algebra.

Next lecture we will massively generalise this to obtain the famous Acyclic Models Theorem. This will allow us to give new cute proofs of several of the more tedious arguments we've done over the course.


Next lecture I will also say a few words about the exam, including more details about exactly what is and is not examinable.

Comments and questions?