The example text about the y combinator looks mistaken to me. It says Y can "find" a fixpoint, and sketches an example of a fixpoint in a numerical function. It

The example text about the y combinator looks mistaken to me. It says Y can "find" a fixpoint, and sketches an example of a fixpoint in a numerical function. It implies Y is doing something like convergence. But that's not what Y is at all. It's called the fix point combinator, yes, but with the assumption you're going to use it in some curried lazy evaluation scheme with higher order functions. All this on ycombinator.com, too!