Parent State ID: 18
State Depth: 7
Action Taken: stack(a, b)
Action Reasoning: The goal is to have block 'a' on block 'b' and block 'd' on block 'c'. Since block 'a' is clear and on the table, we can stack it on block 'b', which is also clear, moving us closer to the goal.
State Description: Block 'a' is on top of block 'b' and clear. Block 'c' is clear and on top of block 'b'. Block 'b' is on the table and supporting block 'a'. Block 'd' is on the table and clear. The hand is empty. In the diagram, block 'a' is now on top of block 'b'.
Action Path: ['unstack(d, a)', 'put-down(d)', 'unstack(a, c)', 'put-down(a)', 'pick-up(d)', 'put-down(d)', 'stack(a, b)']

INACTIVE REASON: deactivated because diagram generation failed or invalid action chosen: Preconditions for stack(a, b) are not satisfied; block b is not clear and the hand is not holding block a.
