Littlewood-Offord theory is the study of random signed sums
of n integers (or more generally, vectors), being particularly
concerned with the probability that such a sum equals a fixed value
(such as zero) or lies in a fixed set (such as the unit ball).
Inverse Littlewood-Offord theory starts with some information about
such probabilities (e.g. that a signed sum equals 0 with high
probability) and deduces structural information about the original
spacings (typically, that they are largely contained within a