Interaction

What kinds of interactions among agents are assumed?

The ability to represent interaction as local instead of global is another key characteristic of ABMs. This concept addresses which agents interact with each other and how. We distinguish two very common kinds of interaction among agents: direct and mediated. Direct interaction is when one agent identifies one or more other agents and directly affects them, e.g. by trading with them, having some kind of contest with them, or eating them. Mediated interaction occurs when one agent affects others indirectly by producing or consuming a shared resource; competition for resources is typically modeled as a mediated interaction. Communication is an important type of interaction in some ABMs: agents interact by sharing information. Like other kinds of interaction, communication can be either direct or mediated. An example of mediated communication is one insect depositing a pheromone that indicates to other insects that food was found. Describe: • The kinds of interaction among agents in the model, including whether each kind is represented as direct or mediated interaction. • For each kind of interaction, the range (over space, time, a network, etc.) over which agents interact. What determines which agents interact with whom? • The rationale for how interaction is modeled.

In the ITC evacuation model:

• Officers sense agents and in case they are not evacuating yet, they will urge them to start to evacuate
• Regular agents sense each other to help others evacuate (leavers help other agents and take them along to an exit)
• Officers can take other agents along when they go to an exit
• Agent does not change the environment
• Interaction occurs through social influence between household agents sharing relationship links. For technology diffusion, adopting peers increases the probability (where this equals not already 1) a household adopts feedback technology. For behavior diffusion, a household agent gradually adapts its energy consumption behavior according to the mean behavior of its peers.
• Cells respond to the local configurations of other cells by moving in response to a pressure gradient or, in the case of LESCs, replicating in response to the death of a neighbor.
• There are two kinds of interaction in this model: between telemarketers and potential customers, and among the telemarketers. The telemarketers interact directly with potential customers by communicating to find out whether the customers will buy, and then by making the customers change their state to indicate that they bought during the current time step. The telemarketers’ interactions with each other are mediated by the resource they compete for: customers. When the territories of telemarketers overlap, customers of one telemarketer are no longer available as potential sales for other telemarketers. Both of these kinds of interaction are local because telemarketers are assumed able to call only customers within a radius of their location. However, this radius increases with telemarketer size (see the “Telemarketer sales” submodel, below) and interaction approaches global for large telemarketers.