Parent State ID: 42
State Depth: 9
Action Taken: pick-up(b)
Action Reasoning: To achieve the goal state, we need to move block b onto block a. Since block a is clear and block b is on the table, we can pick up block b to prepare for stacking it on block a.
State Description: The hand is holding block b. Block a is stacked on block c. Block c is clear, on the table, and supporting block a. Block b is no longer on the table. Block d is on block b and is clear.
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)', 'pick-up(b)']

INACTIVE REASON: Pruned in beam search
