



   

This directory contains the following files:

1. action.pl - SWI-Prolog source code for compiling
causal theories into successor state axioms and 
STRIPS-like systems.

2. instruction - simple instructions on running action.pl

3. blocks.pl - blocks world as given in the paper.

4. blocks1.pl -  another encoding of the blocks world
using the following better known actions: 
pickup(X), putdown(X), stack(X,Y), and unstack(X,Y). 
Of special interest is the preconditions of pickup(X) -
normally this action is intended for the robot to
pickup a block that is on the table and clear, 
so ontable(X) is a precondition. However, if one
deletes this precondition, meaning we allow the 
robot to pick up X from anywhere as long as it is clear, 
then the underlying causal rules will make
this action context-dependent. For instance, 
if X is on Y initially, then Y will be clear afterward.

5. sokoban.pl and sokoban1.pl are our encodings of the
the sokoban domain in the PDDL planning domain library. 
The paper mentions that we do not try to detect any 
consistency conditions in the given action domain 
description. But our implementation has actually some
simple mechanism for detecting impossible actions. 
In this case, if an agent is already at the left-most
column, then the system would detect that the action
of moving the agent one step to its left is an 
impossible action.

6. art-indt.pl - a simple action with indeterminate actions.

7. various other action domain descriptions 
(files with .pl extension) and their corresponding
pddl files.

Comments to flin@cs.ust.hk
http://www.cs.ust.hk/~flin
