Feature Forward Chaining Backward Chaining
When Suggested All or most data is given; large number of potential goals with few achievable; difficult to formulate a goal. Goal or hypothesis is given or easily formulated; large number of rules but goal prunes search space; data must be acquired as necessary.
Advantages Simple. Search is goal directed, only necessary rules are applied.
Disadvantages Many applicable rules at each stage (conflict resolution needed); process not directed towards a goal (stop condition unknown). A goal has to be known.

Conflict Resolution Strategies

Conflict resolution is the method for choosing which rule to fire when more than one rule (the conflict set) can be fired in a given cycle.

Strategy Description
First Applicable Firing the first applicable rule if the rules are in a specified order.
Most Specific Choosing the rule with the most conditions, based on the assumption that a specific rule processes more information.
Least Recently Used Choosing the rule with the earliest time or step mark, which marks the last time it was used.
Highest Priority Choosing the rule with the highest 'weight' assigned to it.
Most Recently Entered Firing the rule whose antecedent uses the data most recently added to the database.