Ontology: Check and potentially reclassify the powerplant class

[l-emele]

Description of the issue

We currently have the following definitions an classifications:

• power generating unit is defined as _A power generating unit is an artificial object that contains a generator, among other parts._ and classified as artifical object. This seems to be correct.
• powerplant is defined as _A powerplant is an aggregate of power generating units that feeds electric energy into an electric grid._ So in the definition we wrote that power plant is an aggregate of objects, but we we classified it as artifical object and not as object aggregate.

Ideas of solution

I suggest to reclassify powerplant in line with its definition to object aggregate.

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

[sfluegel05]

object aggregate has the following editor note: _An entity a is an object aggregate if and only if there is a mutually exhaustive and pairwise disjoint partition of a into objects._
I am not sure if a power plant _is_ a collection of power generating units or just contains some power generating units (and also other things). In the latter case, power plant wouldn't quite fit the definition of object aggregate. An alternative suggestion would be to adjust the definition of power plant and add an axiom has part some power generating unit.

[l-emele]

What exactly is meant with _mutually exhaustive_? I am not sure whether I am understand this correctly. Maybe you can explain this with an example?

Adding has part some power generating unit definitely makes sense.

[sfluegel05]

Another, maybe more clear explanation by the bfo's creators:

An object aggregate is a material entity that is made up of a collection of objects and
whose parts are exactly exhausted by the objects that form this collection.

As I understand it, this means that an object aggregate consists only of the objects and has no additional parts. So for example, the "collection of patients in a hospital" is an object aggregate (this is one of the examples given by the bfo), because the collection only consists of patient-objects and nothing else. On the other hand, a hospital would not be an object aggregate, because it has not just patients, but also doctors, a building, equipment, legal documents, etc. which all together make up the hospital.

[stap-m]

If I recall it right, we defined it like this because a power plant is an aggregate of artificial objects, but the artificial objects are not necessarily of the same kind. The idea was that a power plant constists at least of 1 power generating unit and its connection to the grid.

Adding has part some power generating unit definitely makes sense.

Agreed.

[l-emele]

If I recall it right, we defined it like this because a power plant is an aggregate of artificial objects, but the artificial objects are not necessarily of the same kind.

Right, I remember that too: A power plant can e.g. consist of an coal power unit and a gas fired power unit.

The idea was that a power plant constists at least of 1 power generating unit and its connection to the grid.

We could make this more explicit by reformulating the current definition _A powerplant is an aggregate of power generating units that feeds electric energy into an electric grid._ to _A powerplant is an aggregate of power generating units and a grid component that feeds electric energy into an electric grid._

Adding has part some power generating unit definitely makes sense.

Agreed.

I agree too. If you accept my proposal above, we should also add has part some grid component.

[l-emele]

I got two thumbs up, so I will implement.