Abstract: A computer that includes a processor and a memory, the memory including instructions executable by the processor to train a neural network to input data and output a prediction. A policy can be generated based on the data. Force features can be generated based on the policy. Decision nodes can be trained based on force features and a binary vector from the trained neural network. A decision tree can be generated based on the decision nodes. A decision can be generated by inputting a policy to the decision tree. The decision can be compared to the prediction and the neural network re-trained based on a difference between the decision and the prediction.