Question 22: The domain description of a blocks-world with a single o…

1    armEmpty   The arm is not holding any block, it is empty.
2    holding(X) The arm is holding X.
3    onTable(X) X is on the table.
4    clear(X)   X has nothing above it, it is clear.
5    on(X,Y)    X is directly on Y.

1    Pickup(X): pick up X from the table.
2
3       Preconditions: { armEmpty, clear(X), onTable(X) }
4       Add Effects  : { holding(X) }
5       Del Effects  : { armEmpty, onTable(X) }
6
7    Putdown(X): place X on the table.
8
9       Preconditions: { holding(X) }
10       Add Effects  : { armEmpty, onTable(X) }
11       Del Effects  : { holding(X) }
12
13    Unstack(X,Y): pick up X that is directly sitting on Y.
14
15       Preconditions: { armEmpty, clear(X), on(X,Y) }
16       Add Effects  : { clear(Y), holding(X) }
17       Del Effects  : { armempty, on(X,Y) }
18
19    Stack(X,Y): place X directly on top of Y.
20
21       Preconditions: { holding(X), clear(Y) }
22       Add Effects  : { armEmpty, on(X,Y) }
23       Del Effects  : { holding(X), clear(Y) }