This raises another question: what is <knowledge>? Knowledge is related to identity ("sameness"). Here are some dimensions of knowledge: abstraction <= model <= implementation <= simulation <= emulation <= reproduction <= physical self
1. An abstraction (the simplified and idealized description of the attributes of an object or the behavior of a process) becomes a model when it describes not just the attributes and behavior of an object or process but also how they arise and are implemented.
2. A model (the static description of the physical properties of an object or of the dynamic state sequence exhibited by a process) becomes an implementation when it can be computed, visualized or otherwise instantiated.
3. An implementation becomes a simulation when it can accurately model certain characteristics of physical objects or processes.
4. A simulation becomes an emulation when it can replace a physical object or process (e.g. simulated water can't be used to extinguish physical fire).
5. An emulation becomes a reproduction when its internal state, the physical substrate, which mimics the functionality of a physical object or process, equals that of the physical object or process.
6. A reproduction is the original physical object or process only if it shares its spatio-temporal history.
