Documentation

topic's main category
main Wikimedia category

Description

The main category of a topic. This is the inverse of category's main topic (P301).

Represents

Wikimedia category (Q4167836), category's main topic (Q106528655)

Data type

Item

Corresponding template

Template:Main category (Q6839215)

Template parameter

The label in the appropriate language will be used in templates like en:Template:Commons category and infoboxes that have a link to Commons or to another project.

Domain

All items about topics. (note: this should be moved to the property statements)

Allowed values

Wikimedia category (Q4167836) (note: this should be moved to the property statements)

Example

narratology (Q382451) → Category:Narratology (Q7031395)
Haarlem (Q9920) → Category:Haarlem (Q7427769)
Basshunter (Q383541) → Category:Basshunter (Q8888075)

Robot and gadget jobs

DeltaBot does the following jobs:

<DeltaBot-addValueClaim>

This is the inverse of category's main topic (P301), so based on that claims can be added. Commons category (P373) contains information that can be used to add claims (for example Haarlem (Q9920) already contains a claim to "Category:Haarlem").

Tracking: usage

Category:Pages using Wikidata property P910 (Q30236668)

Lists

Proposal discussion

Current uses

Total	724,925
Main statement	724,856	>99.9% of uses
Qualifier	9	<0.1% of uses
Reference	60	<0.1% of uses

Search for values

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

Single best value: this property generally contains a single value. If there are several, one would have preferred rank (Help)

Exceptions are possible as rare values may exist. Exceptions can be specified using exception to constraint (P2303). Known exceptions: war (Q198)
List of violations of this constraint: Database reports/Constraint violations/P910#single best value, SPARQL

Distinct values: this property likely contains a value that is different from all other items. (Help)

Exceptions are possible as rare values may exist. Exceptions can be specified using exception to constraint (P2303). Known exceptions: carpet (Q163446), rug (Q104602244), public college (Q104694724), public university (Q875538), gender minority (Q11894636), gender non-conformity (Q4135211), Thomas Jefferson University (Q2471216), Philadelphia University (Q3551662), no label (Q115324747), regional committee of CPSU (Q4329294), Film- und Bühnencosmetologe (Q110864961), make-up artist (Q935666)
List of violations of this constraint: Database reports/Constraint violations/P910#Unique value, SPARQL (every item), SPARQL (by value)

Inverse property of “category's main topic (P301)”:
if [item A] has this property (topic's main category (P910)) linked to [item B],
then [item B] should also have property “category's main topic (P301)” linked to [item A]. (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/P910#inverse, SPARQL

Value type “Wikimedia category (Q4167836)”: This property should use items as value that contain property “instance of (P31)”. On these, the value for instance of (P31) should be an item that uses subclass of (P279) with value Wikimedia category (Q4167836) (or a subclass thereof). (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/P910#Value type Q4167836, SPARQL

Conflicts with “instance of (P31): Wikimedia template (Q11266439), Wikimedia category (Q4167836)”: this property must not be used with the listed properties and values. (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/P910#Conflicts with P31, SPARQL

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/P910#Scope, SPARQL

Conflicts with “category's main topic (P301)”: this property must not be used with the listed properties and values. (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/P910#Conflicts with P301, search, 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/P910#Entity types

This entity (P910) is used by Wikimedia's setting of Wikidata. Please contact the development team or file a bug on Phabricator before big changes (renaming, deletion, merging, etc.).

Items with this property should also have either P31 or P279
many lack this (below results are limited to 1000) (Help)
Violations query:

SELECT DISTINCT ?item ?value { 	{ 		SELECT ?item ?value { 			?item wdt:P910 ?value . 			MINUS { ?item wdt:P31 [] } . 			MINUS { ?item wdt:P279 [] } . 		} ORDER BY RAND() LIMIT 1000 	} . }

List of this constraint violations: Database reports/Complex constraint violations/P910#Items with this property should also have either P31 or P279

Items that link to a Commons category
These links should be moved to the category item (Help)
Violations query:

SELECT ?item ?categoryitem ?commonscategory WHERE {   ?item wdt:P910 ?categoryitem .   ?commonscategory schema:about ?item .   ?commonscategory schema:isPartOf <https://commons.wikimedia.org/> .   FILTER REGEX(STR(?commonscategory), "https://commons.wikimedia.org/wiki/Category:") .   } LIMIT 1000

List of this constraint violations: Database reports/Complex constraint violations/P910#Items that link to a Commons category

This property is being used by:

Please notify projects that use this property before big changes (renaming, deletion, merge with another property, etc.)

Discussion[edit]

unknown values for topic's main category[edit]

soon: Basically one should be able to detect pages where the value is "unknown". Similar feature one should be able to detect "no value". לערי ריינהארט (talk) 10:56, 4 November 2013 (UTC)[reply]

Mass constraint violation?[edit]

I noticed that user:Petronas had added the same P910 claim to many items (using Widar of course), and asked them to stop at User_talk:Petronas#P910. They have agreed to stop, but they appear to believe their usage is OK. Could someone else confirm whether the P910 usage in these 1000 contributions is OK? (there are many more similar P910 edits before those 1000) Thanks, John Vandenberg (talk) 08:11, 24 May 2014 (UTC)[reply]

I said I will not continue using topic's main category (P910) in any case. And I will eliminate all edits made. It would be necessary to clearly explain the use. Thanks. Petronas (talk) 08:34, 24 May 2014 (UTC)[reply]

@Petronas, @John_Vandenberg: I looked only at the history of Árraga (Q252457) : FULLURL:Q252457|action=history .

I looked superficially and for me none of the linked pages is a disambiguation page. In this case the addition of topic's main category (P910) is prohibited. Regards gangLeri לערי ריינהארט (talk) 15:51, 24 May 2014 (UTC)[reply]

constraint report relating to Wikimedia disambiguation page (Q4167410)[edit]

If instance of (P31) is a Wikimedia disambiguation page (Q4167410) the presence of topic's main category (P910) is prohibited

see: Wikimedia disambiguation page (Q4167410) with topic's main category (P910) . Usualy there might be two possibilities:

a) please identify the non - ambiguation page (WD item) where the property topic's main category should be moved;
"normally" no other statements should be left at the disambiguation page;
it can happen that a set of properties should be moved to another (a second) WD item, another set to a third WD item etc.

b) verify which language is a disambiguation page and separate it from the rest; please use Gadget-labelLister.js ^{can be activated at preferences#gadgets} to remove all faulty descriptions after the disambiguation page is separated (the languages are de, en, fr, es, pt, pt-br, ru, sv and possibly some others).

Thanks in advance! gangLeri לערי ריינהארט (talk) 15:42, 24 May 2014 (UTC)[reply]

Sometimes (very rare) there are "disambiguation categories" which can be "main category" of disambig. --Infovarius (talk) 10:25, 28 May 2014 (UTC)[reply]

There is also commons:Bolívar, a dab category, and such a dab category my exist in Wikipedias too, so there will be anyway a data item for a dab-category. And there is en:Bolívar (disambiguation) which could be linked, since it has the same topic. At least no non-dab page involved in the example, i.e. a) or b) do not apply.Tamawashi (talk) 12:38, 27 June 2014 (UTC)[reply]

Q10201902[edit]

Please clarify that Q10201902 is not a permitted item for this property, a Wikimedia category found somewhere can't be a good main category for a topic based on Wiki pages and/or a commons category. The data has to make sense on Wikimedia projects in other languages with different ideas of categories. I stumbled over an obscure (=only català has a label) Q10201902 on Freeciv and removed it, but it's still easy to undo that if I got it wrong. –89.15.236.224 06:54, 7 October 2017 (UTC)[reply]

It doesn't matter which languages present at category item and it's main article item. We have a general idea of some notion and general idea of category of the same notion. --Infovarius (talk) 20:46, 8 October 2017 (UTC)[reply]

Update, ca:category:Freeciv was deleted yesterday. Back to the general issue, if a P910 Q10201902 statement boils down to a restatement of a commonscat I think it MUST be removed. –89.15.236.124 12:20, 13 October 2017 (UTC)[reply]

Even in this case I think that it should not be removed. Because every corresponding category item should be linked with P910 (there is no word here about Commons link at all). --Infovarius (talk) 14:16, 13 October 2017 (UTC)[reply]

Finally I got it, sorry: P910 is the inverse of P301, and Q10201902 is a special case using Q424271 as P301. Completely off topic here, as long as Q10201902 exists it needs a P910 on Freeciv.

I think that this discussion is resolved and can be archived. If you disagree, don't hesitate to replace this template with your comment. Infovarius got I right, I completely misunderstood what Q10201902 actually is. –89.15.236.124 15:10, 13 October 2017 (UTC)[reply]

Constraint violation for disambiguation pages and categories[edit]

Just to note that Ajax (Q169527) reports a constraint violation as it has instance of (P31)=Wikimedia disambiguation page (Q4167410), but the correct main category here that should be linked using topic's main category (P910)/category's main topic (P301) is Category:Ajax (Q8229542), which has instance of (P31)=Wikimedia disambiguation category (Q15407973). It's probably too complex a case to include in the constraint violation rules, though. Thanks. Mike Peel (talk) 07:38, 10 October 2019 (UTC)[reply]

History of this property[edit]

Such a property was proposed by me on 6 August 2013, and rejected unanimously (closed by John F. Lewis o 14 August 2013). Most of arguments were based on the claim that we don't need inverse properties. However, despite of it, i was created on 16 September 2013 by Multichill, on the base of his own proposal from 9 September 2013. A really thoughtful and conceptual approach. :-) I congratulate to Multichill on being able to defend and enforce what was rejected to me a month earlier.

The fundamental error was already in the basal design of Wikidata, that complementary properties (symmetric and asymmetric) were not designed to be functionally complementary, so that the inverse function must be complicatedly derived or mirrored. And we have a random chaos of unsystematic properties here.--ŠJů (talk) 14:07, 12 July 2020 (UTC)[reply]

Property talk:P910

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