@Valter: Seconded. I believe

>**Puzzle 36.** Every equivalence relation gives a partition as in [Puzzle 29](https://forum.azimuthproject.org/discussion/1963/lecture-10-the-logic-of-partitions/p1). Show that \\(\approx\\) gives the partition \\(P \vee Q\\).

should say

>**Puzzle 36.** Every equivalence relation gives a partition as in [Puzzle 29](https://forum.azimuthproject.org/discussion/1963/lecture-10-the-logic-of-partitions/p1). Show that \\(\approx\\) gives the partition \\(P \wedge Q\\).