Two objects of fractal dimension 2 will intersect with reasonable probability only in a space of dimension 4 or less, the same condition as for a generic pair of planes.

At present, some of the most successful methods have a reasonable probability of predicting the folds of small, single-domain proteins within 1.5 angstroms over the entire structure.

It begins by documenting a variety of situations in which we either arrive at binary decisions or fail to precisely associate reasonable probabilities to outcomes.