Algorithm

The planning process starts by constructing a partial plan consisting of two steps:

• An initial step with no preconditions and with the initial conditions as its effects;
• A goal step with no effects and with the goal conditions as its enabling preconditions.

Plan(PartList)

1. Choose a partial plan Plan from PartList;
2. If Plan is complete, then finish;
3. If there is an unsafe link Unsafe:
   • Do resolve(Plan, Unsafe) and add the resulting plans to PartList;
   • Return to step 1;
4. If there is an open condition Open:
   • Do establish(Plan, Open) and add the resulting plans to PartList;
   • Return to step 1.

It now remains to describe how threats to unsafe links are resolved and how open conditions are established.

• Resolving Threats to Unsafe Links
• Establishing Open Conditions