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This section describes a simple version of a State Resource Constraint with a symbolic state domain. More specifically, the constraint has the following features:

• The SRC has a finite number of possible states S.
• The TemporalReference variables of connected Precondition Tasks have a domain of integers from 0 to a planning horizon h, and the Precondition Tasks' State variables have a domain of S.
• The TemporalReference variables of connected State Tasks have a domain of integers from 1 to h.
• The SRC has a finite number of possible events that can cause a state change.
• The SRC's synergy mapping is a partial function which maps a set of State Tasks' Contributions to an event.
• The SRC's state transition is a partial function which maps a state and an event to a successor state.
• The state is projected on a timeline of discrete time points from 0 to h according to the connected State Tasks and the initial value of the Current State. If a Sensor Constraint is connected to the SRC's Object, the state at the Current Time c is set to the Current State, regardless of whether there is a valid state transition or not.
• For the state projection, the present state is preserved if it is not possible to derive an event from the set of all State Task Contributions at that time point by the synergy mapping, or if no state transition is possible from the SRC's present state for the derived event.
• If the state required by a connected Precondition Task is not equal to the SRC's actual state at this time point, the SRC's costs are increased by the minimal number of state transitions required to transform the actual state to the required state.

The constraint's internal structures and heuristics are detailed in the following sections.

• Internal Structures
• Selecting an Improvement Heuristic
• SRC-H1: Adding an Event
• SRC-H2: Moving an Event
• SRC-H3: Moving a Precondition
• SRC-H4: Deleting an Event
• SRC-H5: Deleting a Precondition

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Last update:
May 20, 2001 by Alexander Nareyek