Topic on User talk:GerardM

Hi — I'm wondering why you've twice reverted that Sultan of Oman (Q28478447) is subclass of (P279) head of government (Q2285706), leaving it as instance of (P31) instead. This is the only item in all of Wikidata that has a P31 like this:

SELECT DISTINCT ?item ?itemLabel 
WHERE {      
  ?item wdt:P31 wd:Q2285706
  SERVICE wikibase:label { bd:serviceParam wikibase:language "en" . }
}
ORDER BY ?itemLabel

Every other item uses P279:

SELECT DISTINCT ?item ?itemLabel 
WHERE {      
  ?item wdt:P279 wd:Q2285706
  SERVICE wikibase:label { bd:serviceParam wikibase:language "en" . }
}
ORDER BY ?itemLabel

The problem is that quite often the person who holds a title like "Sultan of Oman" is not the head of government. So the notion of it being a subclass is problematic. Also, the sultan of Oman is singular it does not have anything under it.. no instances of. Thanks,

Can you give an example of someone who was Sultan of Oman and not the head of government? That will help work out how to model this.

I'm not sure I understand your point about having no instances. There are also no instances of President of the United States of America (Q11696) or Prime Minister of the United Kingdom (Q14211) or any of the other subclasses of head of government (Q2285706) either. Are you saying that all of those are also incorrect (and thus we need to change all of thus, and update the modelling documentation etc) or is Sultan of Oman (Q28478447) different from those in this regard?

Thanks.

Not necessarily Oman. I have done extensive work on all kinds of Sultans. Some were the Sultan in exile..

For a subclass not to have instances is imho a stretch.

Thanks,

GerardM

Ah, OK. I'm not suggesting making sultan (Q43292) (in the general case) be a head of government (Q2285706), but I think it's accurate for Sultan of Oman (Q28478447).

Having subclasses without instances surprised me too, as my brain is more used to dealing with these terms and concepts in software engineering than in linked data modelling, so I'm certainly open to persuasion that my understanding is completely wrong. But Wikidata has lots of subclasses without instances:

SELECT (COUNT(?child) AS ?count) WHERE { ?child wdt:P279 ?parent }

shows that we have about 2.2M subclasses in Wikidata at the moment.

SELECT (COUNT(?child) AS ?count) 
WHERE {  
  ?child wdt:P279 ?parent FILTER NOT EXISTS { ?instance wdt:P31 ?child }
<nowiki>}</nowiki>

times out, but we can get the first million such items:

SELECT DISTINCT ?child
WHERE {      
  ?child wdt:P279 ?parent
  FILTER NOT EXISTS { ?instance wdt:P31 ?child }
}
LIMIT 1000000

For now I think it's better to have Sultan of Oman (Q28478447) modelled the same way as every other Head of Government entry, so that queries against the data will return consistent results. I'm certainly open to persuasion that we should go through and change all of those to be instances instead of subclasses, but I've just been following what already exists, and faced with at least a million such cases, accepting it's my understanding that's off, rather than the data…

Happy to look at any pointers you can give for how else we could go about this.

I support Oravrattas in having subclass here, not an instance. Actually this class _has_ substances: note that position held (P39) is subproperty of P31, so all people that has P39 Sultan of Oman (Q28478447) effectively have P31 Sultan of Oman (Q28478447).

When you check the "list of sultans of Oman" many were an imam. So the title is not limited to modern Oman and consequently I doubt that "head of government" applies. More strongly, it does not.

In that case we can add a start time (P580) qualifier to the subclass of (P279) — there are many other examples like that, e.g. Bishop of Sherborne (Q680033) or President of Zimbabwe (Q19056184). I don't know the history of Oman well enough to know what that date should be, however. If it's when it switched from being Imam to Sultan, perhaps 1749 would be suitable?

No, you do not get it. The title is still the same. The function is based on religion more than political power. The assumptions about many old titles are not modern .. like office holder.. It is what we use but it is an abstraction that works only well in the modern time.

So, help me understand by making a suggestion for how to solve the problem here. I'm perfectly happy to accept that it only works for modern times — which is exactly why I'm suggesting finding the correct start date to attach to the concept. Another alternative would be to split out a separate item for the modern concept, or for different aspects of the role. That seems a lot more complex, but if we want to be much more precise about this concept than every other example, then perhaps that's the way to go?

"For a subclass not to have instances is imho a stretch." - Who told you so? Psychology is a subclass, has no instances.

A title has no physical existence, so it is a class. It is different from physical things like cars, buildings, ships, humans, plants, animals.

Sultan of Selangor/Brunei/Kelatan/Oman could be a subclass of sultan. For that to be true it must share all properties of "sultan" and have at least one additional property.

I am extremely uncomfortable with many of the notions around classes and classification. Many if not most of them are only a construct in the mind of ... constructs that are impossible to explain for all the prior baggage that is expected to be agreed on