systems theory.md

System

• an interconnected set of elements that is coherently organized in a way that achieves something.

System: {
	elements: [Element]
	interconnections: [Connection]
	purpose: Purpose
}

System(Digestive): {
	elements: [Teeth, Enzymes, Stomach, Intestines]
	interconnections: [(Teeth, chew, saliva, Enzymes), ...]
	purpose: "convert food into nutrients and transfer them into bloodstream, while discarding unusable wastes"
}

Stock

• elements of a system that you can see, feel, count, or measure at any given time
• a quantity (accumulation) of material or information that has built up over time
• not necessarily physical
• is the memory of the history of changing flows within the system
• increased by increasing inflow rate (and decreasing its outflow rate)
• decreased by increasing outflow rate (and decreasing its inflow rate)
• act as delays or buffers (queues?)

Flow

• fill and drain stocks

Clouds

• unknown (or unimportant) sources and sinks for flows

Charts

• plot changes of variables overtime, either stocks or flows

Feedback loop

• a closed chain of causal connections from a stock, through a set of decisions or rules or physical laws or actions that are dependent on the level of the stock, and back again through a flow to change the stock