Figure shows loss, , and integer loss, I , for hCRNNs with a differing number of presumed elementary reaction steps, n. As described above, this hyperparameter has to be chosen by the user and is critical for the network to identify the reactions pathways within the mechanism. To select a fitting value, n is linearly increased during a hyperparameter search and the error metrics of the trained network are observed during screening. Generally, small losses, , indicate overall low errors for formation rate predictions, while low integer losses, I , indicate very little deviation from integer stoichiometric coefficients and thereby the elementary-step assumption. For the chosen reaction network, the loss significantly decreases between n = 3 and n = 5 while the integer loss shows the opposite behavior. Focusing only on overall loss might lead the reader to choose the local (possibly global) minimum at n = 5 and consequently assume 5 elementary reactions, neglecting the fact that decrease in loss from n = 4 to 5 is far less significant than that from n = 3 to 4. At the same time the strong rise in integer loss I indicates the presence of at least one row with a stoichiometric coefficient far from the next integer (for explicit results the reader is referred to appendix SI C). Experience shows that this typically coincides with completely chaotic stoichiometric coefficients in that row. Both facts combined reveal the overall tendency repeatable throughout all conducted experiments: If too