mekso at-most-4-ary operator: integer lattice ball; the set of all points belonging to the intersection of Zn with the closure of the ball that is centered on X1 and has radius X2 in metric X3, where Z is the set of all integers and where, for any set A and non-negative integer n,
An is the set of all n-tuples such that each coordinate/entry/term belongs to A, and where the dimensionality n = X4..