I like the first one. It's all,
It is pitch black. Your backtracking nondeterminism is likely to be eaten by a grue cut.
Concerning the second, I was pleasantly surprised to find out from wikipedia this morning that the definition of irreducible closed sets is connected to both algebraic geometry (since a variety is defined as an irreducible algebraic set) and pointless topology, since sober spaces are characterized by being those where any irreducible closed subset of X is the closure of exactly one singleton of X.