Strips Planning Systems -Plans with Run-Time Conditionals
- Perceptual processes are used to refine the state descriptions while we are executing the plan inorder to generalize the formulas which are allowed in state descriptions.
- Let us consider an example in which the state description formula contains disjunctions i.e. like On(Q, P) v On(Q, R). Here Q can be on P or Q can be on R. It is not known' which of it is true while generating the plan.
- If the STRIPS operators does on have an effect on On(Q, P) v On(Q, R) then they are just carried to after-action state description without knowing which of them is true.
- If the STRIPS operators have any one of On(Q, P) v On(Q, R) are conditions before the action which have to be considered then it has to be known that which of the conditions is true.
- The determination of which condition is true is carried out by perceptual process.
- A run-time conditional is set in the plan, if such operations which has to know which of the conditions are true has to be applied.
- The presence of run-time conditional splits the plan into branches, in this example two branches will be present one branch has On(Q, P) as true and other has On(Q, R) as true.
- These branches are individually called as context.
- The perceptual process detects which of the disjuncts is true when there is a split into two or more contexts and correct path is chosen.
- The perceptual process uses the results of the actions which are already performed to know the trueness of the disjuncts.
- When the information about the disjuncts is needed the system may use information gathering actions to know the information.
- In the example we considered inorder to know which disjunct is true the actions which can read the letter on the discs have to executed to know the truth. Such operations may be represented as "know which".
