  Deep learning has largely improved the performance of various natural
language processing (NLP) tasks. However, most deep learning models are
black-box machinery, and lack explicit interpretation. In this chapter, we will
introduce our recent progress on neuro-symbolic approaches to NLP, which
combines different schools of AI, namely, symbolism and connectionism.
Generally, we will design a neural system with symbolic latent structures for
an NLP task, and apply reinforcement learning or its relaxation to perform
weakly supervised reasoning in the downstream task. Our framework has been
successfully applied to various tasks, including table query reasoning,
syntactic structure reasoning, information extraction reasoning, and rule
reasoning. For each application, we will introduce the background, our
approach, and experimental results.
