Parent State ID: 8
State Depth: 5
Action Taken: stack(a, b)
Action Reasoning: The goal is to have block 'a' on top of block 'b'. Since block 'a' is clear and on the table, and block 'b' is clear and on the table, the next best action is to stack 'a' on 'b'.
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 clear and on top of block 'b'. Block 'd' is on the table and clear. The hand is empty.
Action Path: ['unstack(d, a)', 'put-down(d)', 'unstack(a, c)', 'put-down(a)', 'stack(a, b)']

INACTIVE REASON: deactivated because diagram generation failed or invalid action chosen: Preconditions for the stack action are not satisfied.
