The name of the puzzle is n-queens.
Load init-rooks.
Ok.
The name of an action is place-block.
You can move a clear available block onto a clear location.
If a block is not on a location then it is available.
If a location is not below an object then it is clear.
The solution has four steps.
Load fail-queens.
The name of a failure is placed-same-row.
Ok.
If two of the blocks are placed and they have the same row then you lose.
If a block is on a location then the block is placed.
The name of a failure is place-same-col.
Ok.
If two of the blocks are placed and they have the same column then you lose.
The name of a failure is place-same-diag.
Ok.
If two of the placed blocks are cross-diagonal then you lose.
If the difference of the rows of the blocks is equal to the difference of the columns of they then they are cross-diagonal.
Load final-queens.
The name of the goal is all-placed.
Ok.
The goal is that all blocks are placed.
Done.
No.