@shoofle arguably my whole line of billiards research is a proof of concept for ideas that were originally motivated by computational complexity and its imo underexplored links to entropy and communication complexity and type theory
it's... arguably rather a long diversion, for a proof of concept, but maybe someday it will circle back xD
@shoofle fun fact: take any (possibly infinite, etc) surface. consider the group of closed paths on it. pick any set of generators for the group.
the growth rate of the number of distinct possible paths by taking the product of n generators depends (up to constant factor) only on the surface, not on the generators u chose.
(in particular, it will be either polynomial or exponential, depending on whether the surface is hyperbolic)