Back-Chainer 1. Pick an unachieved goal or precondition literal l Decision point: Choose an unachieved literal 2. Pick an operator op that achieves l Decision point: Choose an operator that achieves this literal 3. Add op to the plan and establish a link from op to l 4. Instantiate the free variables of Decision point: Choose an instantiation for the variables of the operator: Table 2 Backward-chaining algorithm