“…An important practical test of correctness, intended to distinguish a neural network that merely fits a few Gaussians to the data set from a network that is a Fredholm solver, would be to present a DEER trace with four distances to a network that was trained on a database with at most three. A network that has learned to be a Fredholm solver in the sense discussed in ( 51 , 52 , 54 , 55 , 57 ) should still return the right answer. As Fig.…”