Lattice congruences for combinatorialists
We will begin with the basic facts about congruences on finite lattices that every combinatorialist should see, emphasizing the ideas most relevant to the weak order on a finite Coxeter group (and also to the framing lattices that will appear in Martha Yip's lectures). We apply these facts to the weak order, motivated by examples, and develop the combinatorics of congruences/quotients, in general and in specific. If time allows, we will place the lattice theory in the geometric setting of hyperplane arrangements, posets of regions, and shards.