What is Neural-Symbolic Integration?

Historically, the two encompassing streams of symbolic and sub-symbolic stances to AI evolved in a largely separate manner, with each camp focusing on selected narrow problems of their own. Originally, researchers favored the discrete, symbolic approaches towards AI, targeting problems ranging from knowledge representation, reasoning, and planning to automated theorem proving. While the particular techniques in symbolic AI varied greatly, the field was largely based on mathematical logic, which was seen as the proper ("neat") representation formalism for most of the underlying concepts of symbol manipulation. With this formalism in mind, people used to design large knowledge bases, expert and production rule systems, and specialized programming languages for AI. These symbolic logic representations have then also been commonly used in the machine learning (ML) sub-domain, particularly in the form of Inductive Logic Programming (discussed in the previous article), which introduced the powerful ability to incorporate background knowledge into learning models and algorithms. Amongst the main advantages of this logic-based approach towards ML have been the transparency to humans, deductive reasoning, inclusion of expert knowledge, and structured generalization from small data.