Lecture
This lecture delves into the concept of the push out product, a general construction involving two maps and the formation of a square. The push out product is explored in the context of vibrations, specifically when dealing with arbitrary and specific code vibrations. The instructor demonstrates how to construct push out squares and rectangles, emphasizing the importance of composing push outs. The lecture concludes with a lemma that highlights the relationship between push outs and homotopy equivalences, setting the stage for further exploration of homotopy invariants.