Mock data distribution projected to the x-y-plane as well as the initial correlation functions of each sub-sample of data. In addition, the reconstructed polynomials for each neuron-sample as selected after training are depicted as red dashed lines in the picture. The gray areas denote the 1, 2 and 3σ_y uncertainties of the reconstruction, respectively. σ_y is the projection of the parameter covariance D to the data space as described by Eq. (13).