In this section, we explain the proposed estimation method we use that does not rely on using GD. Let us first consider a simplification of the problem (which we will remove in the next section): Assume that an oracle provides the target Miller indices for the reciprocal spots in Q ⋆ , i.e., for each q ∈ Q, we are given v q = (h q , k q , l q ) T ∈ Z 3 such that for each q ∈ Q ⋆ , v q coincides with the Miller indices of q (the oracle can give us anything as v q for the spots in Q \ Q * , and we cannot differentiate between them a priori). While this is a seemingly strong assumption, we discuss later how a sampling strategy can simulate such an oracle.