At this point, it is necessary to specify how the inputs to the ML model are represented. Here we specify the domain by storing segment endpoints (interfaces between the two colors) in an ordered vector of fixed dimension (padded with zero-length segments); the number of segments that can be represented is limited by the dimension of the input vector. We use an input vector of at most 64 segment endpoints, which allows 32 segments of each color. Thus the vector corresponding to 𝑁 = 1 in Fig. is (0.125, 0.5, 0.625, 1, 1, . . . ), and we specify the first (leftmost) segment, beginning at 0, to be black.