- Find out how NOAH and HACKER implement their constraint posting planning systems.
- How may the Modal Truth Criterion tell us exactly when a proposition is true? (HINT: See Rich and Knight Ch 13, p 353).
- Compare constraint posting and state space searching as used in planning systems.
- You are trying to bolt two metal pates together and they need to
positioned precisely relative to one another. If we put a bolt in and tighten
it we will be unable to position the parts after doing this. However, if we
position the pieces first we wont have a free hand to insert the bolt.
A solution is clearly to insert the bolt, part tighten it and then position the plates.

- Compare this with the Sussman anomaly problem.
- Solve this problem using Goal Stack planning.
- Solve this problem using Constraint Posting.

dave@cs.cf.ac.uk