In knowledge-based computing, which term best describes a system that applies codified rules to current facts in order to solve a specific problem instance?

Introduction / Context:
Rule-based problem solving is a hallmark of early knowledge-based systems used in domains such as medical diagnosis, troubleshooting, and configuration. The canonical implementation is the expert system, which encodes domain knowledge in rules and applies them to a fact base via an inference engine.

Given Data / Assumptions:

• The system uses a set of IF–THEN rules (production rules).
• Present case facts are matched to rules to infer conclusions or actions.
• The question seeks the specific system type, not the broad field name.

Concept / Approach:
An Expert System (ES) comprises a knowledge base (rules), a working memory (facts), and an inference engine (forward or backward chaining). It applies rules to current information to derive new facts, explanations, or recommendations.

Step-by-Step Solution:

Verification / Alternative check:
Classic systems like MYCIN (medical diagnosis) and XCON (VAX configuration) demonstrate rule-based expert system operation.

Why Other Options Are Wrong:

• AI: an umbrella field including many approaches beyond rules.
• KBS: generic label that could include ES but is less specific; the question calls for the specific type.
• Base rule 0: not a standard term.

Common Pitfalls:
Using ‘‘AI’’ when a specific architecture (expert system) is intended. ES is the best match to rule-application on present facts.

Final Answer:
ES