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Probabilistic AND-OR Attribute Grouping for Zero-Shot Learning
Proceedings of the 34th Conference on Uncertainty in Artificial Intelligence, PMLR R16:381-391, 2018.
Abstract
In zero-shot learning (ZSL), a classifier is trained to recognize visual classes without any image samples. Instead, it is given seman- tic information about the class, like a textual description or a set of attributes. Learning from attributes could benefit from explicitly modeling structure of the attribute space. Un- fortunately, learning of general structure from empirical samples is hard with typical dataset sizes. Here we describe LAGO1, a probabilistic model designed to capture natural soft and- or relations across groups of attributes. We show how this model can be learned end-to- end with a deep attribute-detection model. The soft group structure can be learned from data jointly as part of the model, and can also read- ily incorporate prior knowledge about groups if available. The soft and-or structure suc- ceeds to capture meaningful and predictive structures, improving the accuracy of zero-shot learning on two of three benchmarks. Finally, LAGO reveals a unified formulation over two ZSL approaches: DAP (Lampert et al., 2009) and ESZSL (Romera-Paredes & Torr, 2015). Interestingly, taking only one sin- gleton group for each attribute, introduces a new soft-relaxation of DAP, that outperforms DAP by $\tilde$40%.