  Explaining recommendations enables users to understand whether recommended
items are relevant to their needs and has been shown to increase their trust in
the system. More generally, if designing explainable machine learning models is
key to check the sanity and robustness of a decision process and improve their
efficiency, it however remains a challenge for complex architectures,
especially deep neural networks that are often deemed "black-box". In this
paper, we propose a novel formulation of interpretable deep neural networks for
the attribution task. Differently to popular post-hoc methods, our approach is
interpretable by design. Using masked weights, hidden features can be deeply
attributed, split into several input-restricted sub-networks and trained as a
boosted mixture of experts. Experimental results on synthetic data and
real-world recommendation tasks demonstrate that our method enables to build
models achieving close predictive performances to their non-interpretable
counterparts, while providing informative attribution interpretations.
