> he talks about how its impossible to make an algorithm tile a grid in a certain way. My guess, is that here he is talking about undecidability which appears

> he talks about how its impossible to make an algorithm tile a grid in a certain way. My guess, is that here he is talking about undecidability which appears quite often in mathematical problems, maybe something like this http://en.wikipedia.org/wiki/Wang_tile http://en.wikipedia.org/wiki/Wang_tile or http://www.nd.edu/~svandend/Tilings.pdf http://www.nd.edu/~svandend/Tilings.pdf (pdf).