Ontology: Add is about relation to quantity values

[stap-m]

Description of the issue

From PR #697
We almost never use the axiom something quantity value is about something. Nevertheless, this relation would make the quantity value subclasses more transparent.

Ideas of solution

Add the is about relation to all quantity values to relate them to the respective concepts they are about.
Maybe it would be possible to add is about as non-reflexive inverse of has quantity value.

Workflow checklist

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

I am aware that

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

[l-emele]

I don't understand what you mean with _non-reflexive inverse_. Can't we define a simple inverse quantity value of like we have has input and input of?

[stap-m]

If I understood @jannahastings right, the relation that is usually used for quantity values is is about. Anyway, is about is quite a broad relation and we use it for other concepts, too.

[jannahastings]

Yes, is about is usually used for quantity values. But we could define a sub-property of is about just for quantity values and call it quantity value of if we prefer?

[stap-m]

Sounds like a practical solution.

[stap-m]

I can implement.
One question: is about is part of oeo-model. But at least its subrelation quantity value of should point at classes from oeo-physical. Is this a problem? Or should the relation(s) be moved to oeo-shared?

[sfluegel05]

I think is about should get included in oeo-shared. Currently, is about is part of the iao-module, which is only imported in oeo-model. The other external ontologies / modules (ro, omo, uo, bfo) are all imported in oeo-shared, so we should probably do the same with the iao-module.

[sfluegel05]

https://github.com/OpenEnergyPlatform/ontology/pull/710#issuecomment-822437565:

It's just that the relations between the quantity values and the "entities in reality" are not yet added. I was wondering, if this sould be done automatically or manually.

I don't think there is much here that can be done automatically, because 'hub height' SubClassOf 'has quantity value' some 'length value' doesn't entail 'length value' SubClassOf 'quantity value of' some 'hub height'. Or in other words: even if we know that an entity in reality is connected to a specific quantity value we still have to define to which entities in reality the quantity value can be connected.

I also don't think that we need to connect every quantity value to a certain set of entities in reality, but here are some axioms I found based on the existing textual definitions / other axioms:

• coefficient of performance value SubClassOf quantity value of some energy conversion performance
• declared net capacity SubClassOf quantity value of some power generating unit or power plant
• duration SubClassOf quantity value of some one-dimensional temporal region (instead of is about some one-dimensional temporal region)
• emission quantity value SubClassOf quantity value of some emission value
• nameplate capacity SubClassOf quantity value of some power generating unit or power plant
• power rating SubClassOf quantity value of some energy converting device
• storage capacity SubClassOf quantity value of some energy storage object

[sfluegel05]

This issue has been solved in PR #710, so I will close it.