Wasserstein is all you need
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We propose a unified framework for building unsupervised representations of individual objects or entities (and their compositions), by associating with each object both a distributional as well as a point estimate (vector embedding). This is made possible by the use of optimal transport, which allows us to build these associated estimates while harnessing the underlying geometry of the ground space. Our method gives a novel perspective for building rich and powerful feature representations that simultaneously capture uncertainty (via a distributional estimate) and interpretability (with the optimal transport map). As a guiding example, we formulate unsupervised representations for text, in particular for sentence representation and entailment detection. Empirical results show strong advantages gained through the proposed framework. This approach can be used for any unsupervised or supervised problem (on text or other modalities) with a co-occurrence structure, such as any sequence data. The key tools underlying the framework are Wasserstein distances and Wasserstein barycenters (and, hence the title!).
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