Domain and range of `is traded at` and `trades`

[l-emele]

Description of the issue

In PR #1127, the two object properties is traded at and trades got the domain/range good or commodity or service. However this does not fully reflect the definition which also includes financial instruments.

Ideas of solution

Once, a class financial instrument is implemented, extend domain/range of is traded at and trades. As we currently have not yet started discussion a discussion on financial instrument, this issue intentionally does not yet get a milestone.

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]

financial instrument is part of the issue:

• #1545

[l-emele]

financial instrument is part of the issue:

* [Subclasses of `policy instrument` #1545](https://github.com/OpenEnergyPlatform/ontology/issues/1545)

That was a mistake. The issue contains fiscal instrument, but that is not the same as financial instrument.

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In PR #1748 we introduced service: A service product is an immaterial entity that has the service product role. In issue #1514 I just proposed to add the axiom 'service product' 'has role' some 'good role' which would make service product a subclass of good.

A financial instrument will be most likely a service product or at least an immaterial good which I also proposed in issue #1514 and if it is tradeable at a market exchange it will get the commodity role. So basically everything that is tradeable at market exchange is a commodity.

So as we will have this improved structure of, we can shorten the definitions to:

• is traded at: Is traded at is a relation that holds between a market exchange and ~the financial instruments,~ commodities ~, or other products, services, or goods~ which are traded there.
• trades: A relation that holds between ~financial instruments,~ commodities ~, or other products, services, or goods~ and a market exchange.

Further we can simplify domains and ranges:

• good or commodity or service to commodity
• 'has role' some 'market exchange role' to market exchange