Parent State ID: 31
State Depth: 10
Action Taken: stack(a, b)
Action Reasoning: To achieve the goal state, we need to place block 'a' on block 'b'. Since block 'a' is currently held, the next logical step is to stack it on block 'b', which is clear and on the table.
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)', 'pick-up(a)', 'stack(a, b)']

INACTIVE REASON: deactivated because diagram generation failed or invalid action chosen: Block `c` should not be on block `b` in the new state.
