controlled by the algorithm and something simply statistical so there's of course this problem is challenging in both aspects the optimizations non-convex non-smooth the global landscape right nothing is very good about it lots of local minima and just in general it's difficult the reason about the only thing we can see are really gradients at Hessians and so forth local information and you want to draw global conclusions on the statistical side similarly bad there's more parameters than samples that generalization error literally