As mentioned previously, we will mainly go through examples that require short delay feedback inside gen~. This still is a vast field, and we will try to narrow it down further by exploring physical modeling at this point since gen~ is an exceptionally well-suited tool for it.
Physical modeling means observing physical phenomena and trying to simulate it using digital systems with the aim of synthesizing their sound. Obviously, this is quite a difficult task, and also, often a very CPU-consuming one. Physical modeling, therefore, often deals with simplifications. Also, it might be a hard task to describe real physical systems as differential equations in the first place, so in practice, we'd rather translate differential equations to digital systems or try to find digital algorithms right away and modify them.