Topology IV.b - homotopy theory

Homework for the semi-flipped class: Please read Section 4, 4.1-4.5, about relative homotopy groups, or alternatively watch the 24 first minutes of the next video (Lecture 04.1):

https://mediaspace.epfl.ch/media/Relative+Homotopy+Groups%2C+Lecture+04.1/0_rgz076o1

This introduces the basic definitions homotopy groups of pairs of spaces, we will see together that they assemble into various long exact sequences. The objective is to finish Chapter II and introduce the notion of polyhedra at the beginning of Chapter III.