  In recent decades, machine learning has provided valuable models and
algorithms for processing and extracting knowledge from time-series surveys.
Different classifiers have been proposed and performed to an excellent
standard. Nevertheless, few papers have tackled the data shift problem in
labeled training sets, which occurs when there is a mismatch between the data
distribution in the training set and the testing set. This drawback can damage
the prediction performance in unseen data. Consequently, we propose a scalable
and easily adaptable approach based on an informative regularization and an
ad-hoc training procedure to mitigate the shift problem during the training of
a multi-layer perceptron for RR Lyrae classification. We collect ranges for
characteristic features to construct a symbolic representation of prior
knowledge, which was used to model the informative regularizer component.
Simultaneously, we design a two-step back-propagation algorithm to integrate
this knowledge into the neural network, whereby one step is applied in each
epoch to minimize classification error, while another is applied to ensure
regularization. Our algorithm defines a subset of parameters (a mask) for each
loss function. This approach handles the forgetting effect, which stems from a
trade-off between these loss functions (learning from data versus learning
expert knowledge) during training. Experiments were conducted using recently
proposed shifted benchmark sets for RR Lyrae stars, outperforming baseline
models by up to 3\% through a more reliable classifier. Our method provides a
new path to incorporate knowledge from characteristic features into artificial
neural networks to manage the underlying data shift problem.
