Usually, rule-based systems incorporating symbolic knowledge processing.

Example: If-then rules.

Note: E.g. symbolic, formal representation of knowledge in AI systems, with the ability to infer new knowledge from formal knowledge by means of reasoning based on logic.

ISO/IEC DIS 22989 AI system (3.1.4) that encapsulates knowledge provided by a human expert in a specific domain to infer solutions to problems

ISTQB - CTAI Syllabus An AI-based system for solving problems in a particular domain or application area by drawing inferences from a knowledge base developed from human expertise.