PRODIGY: Alpine

Description

• Alpine is used by PRODIGY to create plans at higher level of abstractions. This allows PRODIGY to ignore unimportant details when forming initial plans, and then fill in the details in subsequent refinements.
• PRODIGY defines a "monotonic" abstraction space to be one in which the refinement of a plan based on the space does not alter the plan.
• Alpine creates a hierarchy of monotonic abstract spaces by removing classes of literals from the domain. Each level of literals only interact with other literals from its own or a lower level.
• Alpine then creates a plan in the highest level of abstraction, and then continually refines the plan into lower levels until all the literals have been considered.
• Alpine creates its hierarchy of abstraction spaces when it first encounters a domain, and saves them for later use.