  Theoretical distributed computing is primarily concerned with classifying tasks according to their difficulty. Which tasks can be solved in a given distributed computing model? We consider here two important tasks: set agreement and weak symmetry breaking. It turns out that the immediate snapshot protocols of Chapter 0 cannot solve these tasks. Moreover, we will identify a broader class of protocols called _manifold protocols_ that cannot solve  -set agreement. (The impossibility proof for weak symmetry breaking is more complicated and is deferred to Chapter 00.)  