EXCALIBUR
Adaptive Constraint-Based Agents in Artificial Environments

[SYMBOLIC SRC]   [Structures]   [Selection]   [SRC-H1]   [SRC-H2]   [SRC-H3]   [SRC-H4]   [SRC-H5]

[ Please note: The project has been discontinued as of May 31, 2005 and is superseded by the projects of the ii Labs. There won't be further updates to these pages. ]

SRC-H5: Deleting a Precondition

(Related publication: [PUBLink])

This heuristic is applicable if there is at least one inconsistent Precondition Task that is not connected to the Task Constraint SGoals. The idea is to delete an action if it is very hard or impossible to fulfill its precondition.

Selecting an Inconsistent Precondition Task

One of the SRC's inconsistent Precondition Tasks that are not connected to the Task Constraint of SGoals is selected with a choice probability for a Precondition Task that is proportional to the inconsistency caused by the Precondition Task. If one of the Action Tasks that belong to the chosen Precondition Task's Task Constraint is currently under execution or has already been executed, and one of the Task Constraint's State Tasks still comes after c, the heuristic is stopped and a negative success value is returned.

Deleting the Corresponding Task Constraint

The Task Constraint of the selected Precondition Task is deleted (together with its tasks).


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Last update:
May 20, 2001 by Alexander Nareyek