Differentiable Submodular Maximization

Differentiable Submodular Maximization

Sebastian Tschiatschek, Aytunc Sahin, Andreas Krause

Proceedings of the Twenty-Seventh International Joint Conference on Artificial Intelligence
Main track. Pages 2731-2738. https://doi.org/10.24963/ijcai.2018/379

We consider learning of submodular functions from data. These functions are important in machine learning and have a wide range of applications, e.g. data summarization, feature selection and active learning. Despite their combinatorial nature, submodular functions can be maximized approximately with strong theoretical guarantees in polynomial time. Typically, learning the submodular function and optimization of that function are treated separately, i.e. the function is first learned using a proxy objective and subsequently maximized. In contrast, we show how to perform learning and optimization jointly. By interpreting the output of greedy maximization algorithms as distributions over sequences of items and smoothening these distributions, we obtain a differentiable objective. In this way, we can differentiate through the maximization algorithms and optimize the model to work well with the optimization algorithm. We theoretically characterize the error made by our approach, yielding insights into the tradeoff of smoothness and accuracy. We demonstrate the effectiveness of our approach for jointly learning and optimizing on synthetic maxcut data, and on real world applications such as product recommendation and image collection summarization.
Keywords:
Machine Learning: Probabilistic Machine Learning
Machine Learning Applications: Applications of Supervised Learning