Define multi-entity simulation.

Multi-entity simulation refers to a type of simulation that involves multiple types or categories of entities that interact with each other within a given system. In this context, entities can represent various components, such as customers, servers, machines, or any other elements that play distinct roles in the simulation.

The ability to simulate various entities is crucial because it allows the model to capture the complexity and dynamics of real-world systems where different types of entities interact and influence one another. For example, in a queueing model, you might simulate customers arriving at a service point, while also modeling the servers that process these customers. This interaction is key to understanding the overall performance of the system.

To further clarify the other options: a simulation involving a single entity type would not qualify as multi-entity, as it lacks the diversity in components necessary to analyze interactions. Similarly, a simulation with no interacting components would only represent isolated entities, which does not reflect the complexities often found in practical scenarios. Lastly, the notion of a simulation that runs only once does not pertain to the concept of multi-entity simulation since it speaks more to the methodology of execution rather than the variety and interaction of entities involved.