Expert Systems Questions and Answers

Answer: A

Rete is Forgy's matching algorithm from the OPS production systems, developed independently of the MYCIN line. EMYCIN was MYCIN's shell, TEIRESIAS its knowledge acquisition assistant, and certainty factors its uncertainty calculus. Grouping the descendants correctly is worth doing once, because examination questions frequently mix members of the two families to see whether the distinction is held. The shared properties explain why these belong to one family, and the differences explain why more than one exists.

Answer: B

A WHY query is answered by the explanation facility, which names the rule whose condition the question is trying to establish, and repeated WHYs climb the goal stack towards the top-level hypothesis. The engine, working memory and the acquisition tools do other jobs. The facility turns what would otherwise feel like an arbitrary interrogation into a visibly purposeful line of enquiry.

Answer: C

The order supplies many facts and the space of possible configurations is far too large to enumerate as hypotheses, so chaining forward from the data is the natural regime, which is exactly what XCON did. Backward chaining suits a short candidate list, and the other two are different paradigms. Matching regime to task shape is the recurring design lesson of this topic.

Answer: D

Brittleness is the collapse of performance just outside the intended domain, made worse by the system's inability to recognise that it has left familiar ground. Circularity and redundancy are structural defects of the rule base, and the acquisition bottleneck concerns building rather than running. Graceful degradation, which human experts show and rule bases do not, is the property that is missing. Most errors here come from carrying a result across from a neighbouring case where it does not hold.

Answer: A

Working memory is the short-term store, cleared between consultations, against which rule conditions are matched. The knowledge base is the long-term store of domain rules, the explanation facility reports on reasoning, and a rule index is an implementation convenience. Holding the two stores apart in your mind is the prerequisite for understanding every algorithm in this topic.

Answer: B

What remains is the shell: engine, explanation facility, working memory and authoring tools, ready to receive a different domain's knowledge. EMYCIN was produced from MYCIN in exactly this way and showed that the architecture rather than the medicine was the reusable asset. The other options name a specific system's uncertainty machinery, a transient state and a single component.

Answer: C

The cycle runs retrieve, reuse, revise, retain, which in the numbering given is 2, 4, 1, 3. Retrieval finds the most similar stored case, reuse adapts its solution, revision corrects it against the actual outcome, and retention adds the corrected case to the library. The final step is what gives case-based reasoning its capacity to improve with experience, which a static rule base lacks entirely. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision.

Answer: D

Domain selection comes first, since an unsuitable task cannot be rescued later, then elicitation, then encoding, then validation against expert judgement, giving 2, 4, 1, 3. The phases in practice iterate rather than run once, with validation sending the engineer back to elicitation. Rapid prototyping, rather than a single pass, was the characteristic development style of the field.

Answer: A

MYCIN chained backward and scored its conclusions with certainty factors, XCON chained forward because its data arrived with the order, and DENDRAL generated candidate structures and tested them against the spectrum. Each method matched the shape of its task, which is the point of learning the three together rather than as isolated historical facts.

Answer: B

The engine controls which rules are applied, the knowledge base stores them, and the explanation facility reports afterwards on what fired. The separation of these three roles is the architectural commitment that distinguishes an expert system from a conventional program, and every other property of the field, from shells to explanation, follows from keeping them apart.