Tuesday, 2 October 2018

Conflict Resolution in AI

  • We have two rules, Rule 2 and Rule 3,  with the same IF part. Thus both of them can be set to fire when the condition part is satisfied.These rules represent a conflict set. The inference engine must determine which rule to fire from such a set. A method for choosing a rule to fired in a given cycle is called conflict resolution.
  • In  forward chaining, BOTH rules would be fired.
  • Rule 2 is fired first as the topmost one, and as a result, its THEN part is executed and linguistic object action obtains value stop.
  • However, Rule 3 is also fired because the condition part of this matches the fact 'traffic light' is red, which is still in the database.As a consequence, object action takes new value go.
Methods used for conflict resolution
  • Fire the rule with the highest priority. In simple applications, the priority can be established by placing the rules in an appropriate order in the knowledge base. Usually this strategy works well for expert systems with around 100 rules.
  • Fire the most specific rule. This method is also known as the longest matching strategy. It is based on the assumption that a specific rule processes more information than a general one.
  • Fire the rule that uses the data most recently entered in the database.
  • This method relies on time tags attached to each fact in the database.In the conflict set, the expert system first fires the rule whose antecedent uses the data most recently added to the database.

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