How to compare two functions for equivalence, as in (λx.2*x) == (λx.x+x)?
Depending on the context, it might be a good idea to use the probabilistic approach: feed it a predefined number of variables and see if the results match.A similar method is used in matrices to compute AB =? C in O(n^2) time (you check a predefined number of rows). You get O(n^2.something) if you do the actual multiplication