Entity contrastive learning in a large-scale virtual assistant system

Conversational agents are typically made up of domain (DC) and intent classifiers (IC) that identify the general subject an utterance be-longs to and the specific action a user wishes to achieve. In addition, named entity recognition (NER) performs per token labeling to identify specific entities of interest in a spoken utterance. We investigate improving joint IC and NER models using entity contrastive learning that attempts to cluster similar entities together in a learned representation space. We compare a full virtual assistant system trained using entity contrastive learning to a baseline system that does not use contrastive learning. We present both offline results, using retrospective test sets, as well as online results from an A/B test that compared the two systems. In both the offline and online settings, entity contrastive training improved overall performance against baseline systems. Furthermore, we provide a detailed analysis of learned entity embeddings, including both qualitative analysis via dimensionality-reduced visualizations and quantitative analysis by computing alignment and uniformity metrics. We show that entity contrastive learning improves alignment metrics and produces well-formed embedding clusters in representation space.