Parent State ID: 39
State Depth: 9
Action Taken: unstack(d, b)
Action Reasoning: To achieve the goal state, we need to move block 'b' onto block 'a'. Since block 'a' is clear, we can unstack 'd' from 'b' to free 'b' for stacking on 'a'.
State Description: The hand is holding block 'd'. Block 'b' is clear and on the table. Block 'a' is on block 'c' and is clear. Block 'c' is supporting block 'a' and is no longer clear.
Action Path: ['unstack(c, d)', 'put-down(c)', 'unstack(d, a)', 'stack(d, b)', 'pick-up(a)', 'stack(a, c)', 'unstack(d, b)', 'stack(d, b)', 'unstack(d, b)']

INACTIVE REASON: Pruned in beam search
