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items: Agent-Based Modeling – A Path to simulate everything

Agent-Based Modeling – A Path to simulate everything
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date: 2025-05-21T14:39:00+08:00
description: What is the ABMNow, let's think back to the COVID-19, which was a gut-wrenching disaster. At the beginning, governments of each country wanted to figure out the severity of the virus spreading and tried to build a simulation model to find how many people would be infected and die as a result. Naturally a classic model called SEIR was be used, which was designed to describe the spread and recovery of a disease with an incubation period on a macroscopic scale an equation.SEIR divides the population into four compartments: Susceptible, Exposed, Infectious, Recovered. We can explain the transformation between them by the following four differential equations:$$ \begin{aligned} \frac{dS}{dt} &= -\beta \frac{S I}{N} \\ \frac{dE}{dt} &= \beta \frac{S I}{N} - \sigma E \\ \frac{dI}{dt} &= \sigma E - \gamma I \\ \frac{dR}{dt} &= \gamma I \end{aligned}​ $$Through these equations, we can easily estimate the number of infections that if we get attributes of infection rate β, incubation rate σ, recovery rate γ, total population N, and initial number of each crowd.However, it is not difficult to realize that SEIR still has many limitations and problems. The SEIR model is a holistic description of the whole population, that is to say, it completely ignores the behavioral differences of individuals between the spread of diseases. We certainly can not assume that a salesman who travels around plays the same role in disease spread as a programmer who often works at home.Also, in the real world, all β, σ, γ, N, even other factors are evolving, such as if we lock down the city, of course the β will get down. Of course, we can describe this kind of parameter variation by adding a set of equations, but this becomes impossible to describe too mach parameter variations just by few equations if we wish to add as many factors as possible.Therefore, although the SEIR model is important in the overall description of infectious diseases, it is still powerless in practical simulation because of d…