Backward Chaining 2

• Stacks. Do you understand stacks?
• What happens if you choose rule 2 first?
• What happens if you can't achieve a sub-goal?
• Backtracking: go back to an early state and try a different branch
• Clips doesn't enable backward chaining by default. I've got a limited amount of Question Driven Backward chaining working and we'll do it in the lab.
• You can also have multiple goals added to the stack from one goal rule.
• What would happen if there were nothing in WM and you wanted coffee?