Define the termination criteria

Alchemist supports the possibility to write termination conditions for any simulation. Termination conditions are TerminationPredicates evaluated on the environment after every executed reaction, and, if met, cause the immediate termination of a simulation. The default implementations are located in the it.unibo.alchemist.model.terminators package.

They are defined in the terminate section of the configuration file. Multiple terminators are allowed: the simulation terminates as soon as any of them is satisfied (they are combined in or).

Terminating the simulation after some time

One of the simplest terminators availables allows for declaring a simulation completed when a certain simulated time is reached. In the following example, it is used in conjunction with a number of variables, showing how it’s possible to use such variables to produce batches of simulations terminating at different times.

incarnation: protelis

network-model:
  type: ConnectWithinDistance
  parameters: [30]

deployments:
  - type: Rectangle
    parameters: [100, 62, 15, 95, 200]
    contents:
      - molecule: "source"
        concentration: true
        in:
          type: Circle
          parameters: [107.96487911806524, 102.49167432603535, 10]
    programs:
      - time-distribution: 1 # This is a frequency
        program: >
           import protelis:coord:spreading
           distanceTo(self.getDeviceUID().getId() == 0)
      - program: send

terminate:
  - type: AfterTime
    parameters: 1

Terminating the simulation if the environment is not changing

A terminator is provided for terminating when a simulation is “stable” (nothing changes in terms of positions and nodes’ content). The class implementing it is StableForSteps.