Parent State ID: 49
State Depth: 13
Action Taken: stack(a, b)
Action Reasoning: To achieve the goal state, we need to place block 'a' on top of block 'b'. Since block 'a' is already on the table and clear, we should stack it on block 'b', which is also clear.
State Description: Block 'a' is on top of block 'b' and clear. Block 'b' is on the table and supporting block 'a'. Block 'c' is on top of block 'b' and supporting block 'd'. Block 'd' is on top of block 'c' and clear. The hand is empty.
Action Path: ['unstack(d, a)', 'put-down(d)', 'unstack(a, c)', 'put-down(a)', 'pick-up(d)', 'stack(d, c)', 'unstack(d, c)', 'stack(d, c)', 'unstack(d, c)', 'stack(d, c)', 'unstack(d, c)', 'stack(d, c)', 'stack(a, b)']

INACTIVE REASON: deactivated because diagram generation failed or invalid action chosen: Preconditions for stacking `a` on `b` are not met; `b` is not clear and the hand is not holding `a`.
