Parent State ID: 18
State Depth: 5
Action Taken: unstack(block_b, block_c)
Action Reasoning: To achieve the goal state, where block D is on block C, we first need to make block C clear by unstacking block B from block C. This action follows the requirements, as block B is clear and the hand is empty, aligning both the capability and the goal.
State Description: Block A is on the table and clear. Block B is in the hand and not clear. Block C is on the table and clear. Block D is on the table and clear. The hand is no longer empty, holding block B.
Action Path: ['unstack(block_b, block_c)', 'stack(block_b, block_d)', 'unstack(block_b, block_d)', 'stack(block_b, block_c)', 'unstack(block_b, block_c)']

INACTIVE REASON: action path invalid: The last action "unstack(block_b, block_c)" is invalid because the precondition that the hand must be empty is not met. The hand is already holding block_b, violating the precondition for unstacking.
