Elevators
The idea for this domain came up from the Miconic domain of IPC2, however the domain has been designed from scratch. The scenario is the following: There is a building with N+1 floors, numbered from 0 to N. The building can be separated in blocks of size M+1, where M divides N. Adjacent blocks have a common floor. For example, suppose N=12 and M=4, then we have 13 floors in total (ranging from 0 to 12), which form 3 blocks of 5 floors each, being 0 to 4, 4 to 8 and 8 to 12.
The building has K fast (accelarating) elevators that stop only in floors that are multiple of M/2 (so M has to be an even number). Each fast elevator has a capacity of X persons. Furthermore, within each block, there are L slow elevators, that stop at every floor of the block. Each slow elevator has a capacity of Y persons (usually Y<X).
There are costs associated with each elavator starting/stoping and moving. In particular, fast (accelarating) elevators have negligible cost of starting/stoping but have significant cost while moving. On the other hand, slow (constant speed) elevators have significant cost when starting/stoping and negligible cost while moving. Travelling times between floors are given for any type of elevator, taking into account the constant speed of the slow elevators and the constant acceleration of the fast elevators.
There are several passengers, for which their current location (i.e. the floor they are) and their destination are given. The planning problem is to find a plan that moves the passengers to their destinations while it maximizes some criterion.
The versions of this domain are the following:
- Sequential: The objective function is to minimize the total cost of moving the passengers to their destinations . The total cost is increased each time an elevator starts/stops or moves.
- Time: Each action has a duration. The goal is to minimize the makespan of the plan.
- Time-numeric: Similar to the 'time' version; numeric fluents have been used to represent floors and capacities.
- Net-benefit: Having the passengers to their destinations is a soft-goal. There is a penalty associated with any passenger not being in their destination floor. The penalty is a function of the difference between the origin and the destination floor (it is supposed that the passenger with use the stairs). The objective function is to minimize the total cost expressed as a function of the cost of moving the elevators and the cost of not serving the passengers.
- Net-benefit - numeric: Similar to net-benefit; numeric fluents have been used to represent floors and capacity constraints.