Property talk:P8225

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is metaclass for
all instances of the subject are subclasses of the object

Data type	Item
Domain	metaclass (Q19478619)
Usage notes	use this property to designate what class a specific item is a metaclass for
Example	aircraft model (Q15056995) → aircraft (Q11436) cell type (Q189118) → cell (Q7868) ship type (Q2235308) → ship (Q11446)
See also	metasubclass of (P2445), subclass of (P279), instance of (P31)
Lists	Items with the most statements of this property Count of items by number of statements (chart) Items with the most statements Items with the fewest statements Count of items by number of sitelinks (chart) Items with the most sitelinks Items with the most sitelinks, but no link to one Wikipedia (sample: Welsh Wikipedia, cywiki) Items with the fewest sitelinks Most linked wikis Items with the most identifier properties By value of property Most statements Fewest statements Most sitelinks Most linked wikis Total of sitelinks on items Most identifiers Fewest identifiers Items with no other statements Most recently created items Items with novalue claims Items with unknown value claims Usage history (total) Usage history (main statement) Chart by item creation date Database reports/Complex constraint violations/P8225 Database reports/Constraint violations/P8225 Map Random list
Proposal discussion	Proposal discussion
Current uses	Total 785 Main statement 782 99.6% of uses Qualifier 3 0.4% of uses
Search for values

[create Create a translatable help page (preferably in English) for this property to be included here]

Scope is as main value (Q54828448): the property must be used by specified way only (Help)

Exceptions are possible as rare values may exist. Exceptions can be specified using exception to constraint (P2303).
List of violations of this constraint: Database reports/Constraint violations/P8225#Scope, SPARQL

Property “subclass of (P279)” declared by target items of “is metaclass for (P8225)”: If [item A] has this property with value [item B], [item B] is required to have property “subclass of (P279)”. (Help)

Exceptions are possible as rare values may exist. Exceptions can be specified using exception to constraint (P2303).
List of violations of this constraint: Database reports/Constraint violations/P8225#Target required claim P279, SPARQL, SPARQL (by value)

Type “metaclass (Q19478619)”: item must contain property “instance of (P31), subclass of (P279)” with classes “metaclass (Q19478619)” or their subclasses (defined using subclass of (P279)). (Help)

List of violations of this constraint: Database reports/Constraint violations/P8225#Type Q19478619, hourly updated report, SPARQL

Allowed entity types are Wikibase item (Q29934200): the property may only be used on a certain entity type (Help)

Exceptions are possible as rare values may exist. Exceptions can be specified using exception to constraint (P2303).
List of violations of this constraint: Database reports/Constraint violations/P8225#Entity types

Single value: this property generally contains a single value. (Help)

Exceptions are possible as rare values may exist. Exceptions can be specified using exception to constraint (P2303).
List of violations of this constraint: Database reports/Constraint violations/P8225#Single value, SPARQL

Instances of the metaclass are not subclasses of the class it is for
(experiment, might be a bad idea to add to all) Usually, the metaclass instances should be subclasses of the class it is for, for example « car models » instances are subclasses of car or mass produced cars. (Help)
Violations query: select ?metaclass ?subtype ?type { ?metaclass wdt:P8225 ?type filter (?metaclass not in (wd:Q16521)) # removing « taxons » because there is way to many of them to complete the query ?subtype wdt:P31 ?metaclass . minus { ?subtype wdt:P279+ ?type . } }
List of this constraint violations: Database reports/Complex constraint violations/P8225#Instances of the metaclass are not subclasses of the class it is for

Constraints

@ChristianKl: I can remove the constraints if you want, though I think some may be good, if you want any others please say. I think the value-requires-statement constraint (Q21510864) constraint is possibly wrong. Iwan.Aucamp (talk) 22:58, 19 May 2020 (UTC)

• @Iwan.Aucamp: Given that instance of (P31) is not transitive, fixed-order metaclass isn't a good constraint. I think subclass of (P279) metaclass is a good constraint. ChristianKl ❪✉❫ 09:31, 20 May 2020 (UTC)

support for this property

Is there any support for this property? Given its intended meaning it would be useful to have some mechanism that would add a subclass of (P279) statement for each instance of a class that has a value for this property. Peter F. Patel-Schneider (talk) 09:16, 14 August 2023 (UTC)

not fixed-order class

If the underlying class is a variable-order class this is not a fixed-order metaclass so I think the constraint should be removed. Peter F. Patel-Schneider (talk) 09:32, 14 August 2023 (UTC)

Done. Peter F. Patel-Schneider (talk) 21:33, 19 August 2023 (UTC)