Parent State ID: 42
State Depth: 9
Action Taken: unstack(d, b)
Action Reasoning: To achieve the goal state, block b needs to be on block a. Since block a is already on block c and block c is on the table, the next step is to move block b onto block a. This requires unstacking block d from block b first.
State Description: The hand is holding block d. Block b is clear and on the table. Block a is stacked on block c, which is on the table. Block c is clear and supporting block a. Block d is no longer on block b.
Action Path: ['unstack(c, d)', 'put-down(c)', 'unstack(d, a)', 'stack(d, b)', 'pick-up(c)', 'put-down(c)', 'pick-up(a)', 'stack(a, c)', 'unstack(d, b)']

INACTIVE REASON: Pruned in beam search
