Inference Engine

• The Inference Engine compares the rules to working memory.
• It picks a supported rule and fires it.
• There can be more than one supported rule, and this is resolved by a conflict resolution strategy.
• For example if the rules look like
  • if (Feature ?X colour green) and (Feature ?X type fruit) then (Feature ?X subtype Watermelon)
  • if (Feature ?X colour red) and (Feature ?X type fruit) then (Feature ?X subtype Apple)
• and working memory says (Feature X1 colour green), (Feature X2 colour red), (Feature X1 type fruit).
• What rule is applied?
• What happens?
• A rule can be supported more than once.
• A fact can be used to support more than one rule.
• Undo the rule and add the working memory item (Feature X2 type fruit).
• What rule is applied?
• Now what happens?
• Rule Based Systems work on a Recongise Act Cycle
• Roughly, rules are recognised as firable.
• A rule is applied, which may or may not change working memory
• It may have side effects (e.g. print something out or move a robot arm)
• A new set of rules is recognised
• If no rules apply the system is done.
• Why?
• This can change if the system is interactive.
• If it is interactive, WM can change because of the interface and new rules can be applied.