Ad Introduction: I provide a link to a very similar talk which a gave at a math conference in Islamabad in 2019. It continues a bit further into how to construct coloring invariants from transitive groups. It is not necessary to watch, I will tell you later. === Chapter 1: The notions you shall learn and remeber: 1.1,1.2 - definition of a knot (polygon embedded in R3) - elementary moves on polygonal curves - "local" definition of equivalence of knots: a finite sequence of elementary moves - orientation of a knot 1.3 - "global" definition of equivalence of knots: homeomorphism of R3 that transforms K1 into K2 (the proof is by methods of algebraic topology can be omitted) - examples of homeomorphisms - rotation, translation, !! various kinds of twists (ex. 1.3.3) !! - mirror image (plane reflection, which is orientation-reversing) - R3 ---> S3 (1-point compactification) 1.4 - link = a finite collection of knots - ordered (K1,...,Kn) vs. unordered (union of Ki) - makes a difference in equivalence, Murasugi chooses unordered - equivalence of links (two versions) 1.5 - connected sum K1 # K2 (= gluing two knots together) - TO DO: prove that it does not matter where you cut the knot !! - knot decomposition into a onnected sum, indecomposable knots are called prime - Theorem: every knot admits a unique decomposition to prime knots (omit the proof) - (all knots, #) is a monoid --- TO DO: understand the proof !! 1.6 This section is about how to make # a group operation, by weakening the notion of equivalence into something called cobordism. You can skip the section.