Size vs. Amount

[nelekoehler]

Description of the issue

In our meta issue #1875 we discussed, that we should specify our definition of size and that we may need amount as a quality e.g. for population count. So this issue is for discussing that further.

The paper "The Semantics of Extensive Quantities within Geographic Information" by E. Top et. al describes the differences between extensive quantities therefore the difference between magnitude (size) and amount. They describe Amounts as quantities that can be added up to or removed from each other, resulting in a new quantity of which original quantities are parts. For example, a quantity of people can be added up to another quantity of people to form a total sum of people, and the original quantities are parts of the whole. So an amount is an extensional mereological quantity whose domain forms a lattice. (E.g.A spatial region (=amount of space)). (page 7: "Certain kinds of quantities can be added up to or removed from each other, resulting in a new quantity of which original quantities are parts. For example, a quantity of people can be added up to another quantity of people to form a total sum of people, and the original quantities are parts of the whole. We call quantities that can be added up in this way amounts. In our theory, this means that amounts can be summed, be subtracted from and be part of each other. In the following, we will motivate and illustrate the axioms with examples of amounts of space (E.g., spatial regions), amounts of time (E.g.,time intervals), as well as amounts of matter and amounts of objects.")

Magnitude/ Size on the other hand is defined by them as a linearly, monotonically ordered quantity. (E.g.The size of a spatial region or its proportion with 
respect to another region’s size.) The term magnitude, also called impact or size, is used to measure a quantity on a linear scale.

See page 8 of The Semantics of Extensive Quantities:

Ideas of solution

We could use their definitions as an orientation. We could specify our definition of size as follows: Size is a quantity that quantifies the spatial extend/physical magnitude of an entity on a linear scale.

In addition we can implement amount as a new subclass of quality. As a basic definition we could the one provided by AFO: The amount a quality of a whole that is the number of entities that are part of the whole. And then we could elucidate further with the definition by Top et.al.:`An amount is a quality with extensional mereology and with sum, difference and product operators in the form of a mathematical lattice. It can be measured with magnitudes.

Workflow checklist

• [ ] I discussed the issue with someone else than me before working on a solution
• [x ] I already read the latest version of the workflow for this repository
• [ x] The goal of this ontology is clear to me

I am aware that

• [ x] every entry in the ontology should have a definition
• [ x] classes should arise from concepts rather than from words

[stap-m]

We could use their definitions as an orientation.

Could you cite the original defs please?

As a basic definition we could the one provided by AFO: The amount a quality of a whole that is the number of entities that are part of the whole.

"a whole" is in oeo terms rather vague. An aggregate of entities? I think we should specify this. Object aggregates can have an amount. "Amount of money" or "amount of energy" are terms that are used. However, for both, I'd need a unit to specify the amount (€, kWh,...). Maybe this is not the kind of amount meant here?

[l-emele]

I understood that amount should be for quantities that are actually countable (like a population) and thus do not have a unit (or only a pseudo unit).

[nelekoehler]

OEO Developer Meeting #86:

• Size is a quantity of an entity that quantifies its spatial extend.
• An Amount is a quality of an object aggregate that counts the number of entities that form the object aggregate.