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Blocks World Planning Examples

What is the Blocks World? -- The world consists of:

We shall use the four actions:

UNSTACK(A,B)
-- pick up clear block A from block B;
STACK(A,B)
-- place block A using the arm onto clear block B;
PICKUP(A)
-- lift clear block A with the empty arm;
PUTDOWN(A)
-- place the held block A onto a free space on the table.

and the five predicates:

ON(A,B)
-- block A is on block B.
ONTABLE(A)
-- block A is on the table.
CLEAR(A)
-- block A has nothing on it.
HOLDING(A)
-- the arm holds block A.
ARMEMPTY
-- the arm holds nothing.

Using logic but not logical notation we can say that If the arm is holding a block it is not empty If block A is on the table it is not on any other block If block A is on block B,block B is not clear.

Why Use the Blocks world as an example?

The blocks world is chosen because:


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Next: Planning System Components Up: Planning I Previous: Search in Planning

dave@cs.cf.ac.uk