Parent State ID: 13
State Depth: 4
Action Taken: stack(block_a, block_b)
Action Reasoning: The goal is to stack block A on block B, which is clear. This action brings us closer to the final stack order.
State Description: Block A is now on block B and is clear. Block B is on block D and is not clear. Block C is on the table and is clear. Block D is on the table and is not clear. The hand is empty.
Action Path: ['unstack(block_b, block_c)', 'stack(block_b, block_d)', 'pick-up(block_a)', 'stack(block_a, block_b)']

successfully verified the action of new state 21 with the path: The last action, stack(block_a, block_b), is valid as all preconditions are met, and it moves the state closer to the goal. The current state's description and visualization accurately reflect the sequence of actions taken.
