Emergence

What key results or outputs of the model are modeled as emerging from adaptive traits, or behaviour, of individuals?

Which system behaviour emergence from behaviour od agent and the environemnt, usually complex system with micro level

This concept addresses a fundamental characteristic of ABMs: that system behavior can emerge from the behavior of agents and from their environment instead of being imposed by equations or rules. However, the degree to which results are emergent or imposed varies widely among models and among the different kinds of results produced by a model. This concept therefore describes which model results emerge from which mechanisms and which results instead are imposed; here, “model results” not only refers to system level dynamics, but also to the behavior of the agents. This element should identify which model results emerge from, or are imposed by, which mechanisms and behaviors, but should not address how such mechanisms and behaviors work; that explanation begins with the following concept. Describe: • Which key model results or outputs are modeled as emerging from the adaptive decisions and behaviors of agents. These results are expected to vary in complex and perhaps unpredictable ways when particular characteristics of the agents or their environment change. • For those emergent results, the agent behaviors and characteristics and environment variables that results emerge from. • The model results that are modeled not as emergent but as relatively imposed by model rules. These results are relatively predictable and independent of agent behavior. • For the imposed results, the model mechanisms or rules that impose them. • The rationale for deciding which model results are more vs. less emergent.

Example: Emergence in the Immigrant Housing Model

Emergence, in this context, refers to the unintended and often complex patterns that arise from the interactions of individual immigrants, landlords, and the housing market. These patterns are not pre-planned or designed but emerge as a consequence of individual decisions and market forces.

What Emerges:

• Spatial Segregation Patterns: Over time, distinct areas within the island of Montreal may emerge where immigrants of similar ethnic origins, languages, and economic statuses tend to cluster.
• Accessibility Zones: Areas with good access to public transportation and schools may become densely populated by immigrants with specific needs (e.g., families with children).
• Economic Clustering: Segregation based on economic status might lead to the formation of economically homogeneous neighborhoods.
• The key outcomes of the model are segregation patterns—especially, how strongly segregated the entire system is; these outcomes emerge from how households respond to unlike neighbors by moving and, to a lesser extent, from the density of households (the percentage of locations that are occupied by a household).
• The model’s primary results—pest insect infestation rates in two types of coffee production—and intermediate results such as bird abundance and spatial distributions of birds emerge from the amount and spatial distribution of the six habitat types, the seasonal abundance of pest insects, the number of birds, and the foraging behavior of birds. Of the nine characteristic patterns used to design and test the model, patterns 3, 4, 5, 7, and 8 especially emerge from bird foraging behavior and habitat characteristics. These patterns are believed driven by the same mechanisms that produce the primary results, so these patterns must also be emergent to make them useful for testing the model’s suitability for its primary purpose. Patterns 1, 2, 6, and 9 are at least partially imposed by model rules and parameters. These four patterns are direct outcomes of lower level processes, especially related to the pest insect’s life cycle, from which other patterns emerge; making these patterns emerge from lower-level mechanisms would make the model much more complex and was determined unnecessary for its purpose.