I'm studing a specific implementation of a recommendation system leveraging on a factorization machine algorithm. For each person_id and item_id combination, I have an implicit rating of 1 or 0 depending on if the user downloaded the content or not. In the base model, I have just utilized as input variables the person_id and the item_id. I selected a latent factor number equal to 5. In the model output, some of the 5 the latent factors associated to some person_id and item_id are negative, and some predictions of the rating for the combination person_id/item_id are negative too. I have searched for some theoretical explanations but not found much material, so here I am.
How a negative latent factor can be explained in this setting? Being the training dataset provided with the target variable equal to 1 or 0, how the model end up with negative predictions for the implicit rating? Many thanks for any hints or material bests