Planning: Two Approaches

Planning Problems

If-add-delete operators
- Preconditions, which must be satisfied for the operator to be performed
- Effects, states which result from the performance of the operator
Establishes links between operator instantiations
Protection: threat to establishes link must either precede operator which establishes threatened condition or follow operator which requires it
Algorithm
- Backward chaining: extending partial plans by finding operators which add uninstantiated preconditions
- Protecting threatened establishes links by creating ordering constraints

Using resolution theorem proving for planning
Situation variables
Operators are functions which take a situation and one or more arguments and return a situation
Initial state and operators are axioms
The frame problem: keeping track of what does not change from one situation to another
Frame axioms: statement about which predicates are not affected by an operator

Last updated: 23 April 1996
URL: http://www.indiana.edu/~gasser/Q351/planning.html
Comments: gasser@salsa.cs.indiana.edu
Copyright 1996, The Trustees of Indiana University