Logic- and knowledge-based approaches focus on the development of systems with logical reasoning capabilities on knowledge to solve an application problem. Such systems typically involve a knowledge base and an inference engine that generates outputs by reasoning on the knowledge base. The knowledge base, which is usually encoded by human experts, represents entities and logical relationships relevant for the application problem through formalisms based on rules, ontologies, or knowledge graphs. The inference engine acts on the knowledge base and extracts new information through operations such as sorting, searching, matching or chaining. Logic- and knowledge-based approaches include for instance knowledge representation, inductive (logic) programming, knowledge bases, inference and deductive engines, (symbolic) reasoning, expert systems and search and optimisation methods.