On Leveraging Variational Graph Embeddings for Open World Compositional Zero-Shot Learning
Muhammad Umer Anwaar, Zhihui Pan, Martin Kleinsteuber
Abstract
Humans are able to identify and categorize novel compositions of known concepts. The task in Compositional Zero-Shot learning (CZSL) is to learn composition of primitive concepts, i.e. objects and states, in such a way that even their novel compositions can be zero-shot classied. In this work, we do not assume any prior knowledge on the feasibility of novel compositions, i.e. open-world setting, where infeasible compositions dominate the search space. We propose a Compositional Variational Graph Autoencoder (CVGAE) approach for learning the variational embeddings of the primitive concepts (nodes) as well as feasibility of their compositions (via edges). Such modelling makes CVGAE scalable to real-world application scenarios. This is in contrast to SOTA method, CGE, which is computationally very expensive. e.g. for benchmark C-GQA dataset, CGE requires 3.94×10^5 nodes, whereas CVGAE requires only 1323 nodes. We learn a mapping of the graph and image embeddings onto a common embedding space. CVGAE adopts a deep metric learning approach and learns a similarity metric in this space via bi-directional contrastive loss between projected graph and image embeddings. We validate the eectiveness of our approach on three benchmark datasets. We also demonstrate via an image retrieval task that the representations learnt by CVGAE are better suited for compositional generalization.