ProtoInfoMax: Prototypical Networks with Mutual Information Maximization for Out-of-Domain Detection

The ability to detect Out-of-Domain (OOD) inputs has been a critical requirement in many real-world NLP applications since the inclusion of unsupported OOD inputs may lead to catastrophic failure of systems. However, it remains an empirical question whether current algorithms can tackle such problem reliably in a realistic scenario where zero OOD training data is available. In this study, we propose ProtoInfoMax, a new architecture that extends Prototypical Networks to simultaneously process In-Domain (ID) and OOD sentences via Mutual Information Maximization (InfoMax) objective. Experimental results show that our proposed method can substantially improve performance up to 20% for OOD detection in low resource settings of text classification. We also show that ProtoInfoMax is less prone to typical over-confidence Error of Neural Networks, leading to more reliable ID and OOD prediction outcomes.