Current State ID: 42
Current State Description: The hand is empty. Block a is stacked on block c. Block c is clear, on the table, and supporting block a. Block b is on the table with block d on top of it. Block d is on block b and is clear.

Child State ID: 52
Action Taken: unstack(d, b)
State Description: The hand is holding block d. Block b is clear and on the table. Block a is stacked on block c, which is on the table. Block c is clear and supporting block a. Block d is no longer on block b.

Child State ID: 53
Action Taken: pick-up(b)
State Description: The hand is holding block b. Block a is stacked on block c. Block c is clear, on the table, and supporting block a. Block b is no longer on the table. Block d is on block b and is clear.

