Knowledge Representation & Logic

AI · Beginner

Definition

Classic AI represents facts and rules in logic so a system can infer new facts.

Foundation of expert systems and reasoning engines.

Diagram

Flowchart

Example: Forward chaining

facts = {'rain'}
rules = [({'rain'}, 'wet'), ({'wet'}, 'slippery')]
changed = True
while changed:
    changed = False
    for cond, res in rules:
        if cond <= facts and res not in facts:
            facts.add(res); changed = True
print(sorted(facts))

Output: ['rain', 'slippery', 'wet']

Key points

Forward chaining: data → goal
Backward chaining: goal → data

Interview questions

Forward vs backward chaining?

Forward derives all facts from data; backward starts at a goal and checks what proves it.