4. Main functionalities for models (**usage tasks**).
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5. Types of models.
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6. Model building process.
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7. Examples of real systems (inside / outside ChemE):
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* World model: [description](https://insightmaker.com/insight/2pCL5ePy8wWgr4SN8BQ4DD/The-World3-Model-Classic-World-Simulation), [Wikipedia](https://en.wikipedia.org/wiki/World3).
