Versa: Versatile and Efficient Few-shot Learning

Despite recent advances in few-shot learning, notably in meta-learning based approaches [Ravi and Larochelle, 2017, Vinyals et al., 2016, Edwards and Storkey, 2017, Finn et al., 2017, Lacoste et al., 2018], there remains a lack of general purpose methods for flexible, data-efficient learning. This paper introduces VERSA, a system for data efficient and versatile meta-learning. It employs a flexible and versatile amortization network that takes few-shot learning datasets as inputs, with arbitrary numbers of shots, and outputs a distribution over task-specific parameters in a single forward pass. VERSA substitutes optimization at test time with forward passes through inference networks, amortizing the cost of inference and relieving the need for second derivatives during training. We evaluate VERSA on benchmark datasets where the method achieves state-of-the-art results, handles arbitrary numbers of shots, and for classification, arbitrary numbers of classes at train and test time. The power of the approach is then demonstrated through a challenging few-shot ShapeNet view reconstruction task.