Property talk:P971

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category combines topics
this category combines (intersects) these two or more topics
DescriptionTwo or more item topics that this category combines. Rather use category's main topic (P301) for single values (one-to-one mappings), and topic's main category (P910) to link back.
Associated item
Data typeItem
Corresponding templateTemplate:Category by (Q42878390)
DomainWikimedia category (Q4167836)
Allowed valuesNot categories - Not Wikimedia category (Q4167836) (note: this should be moved to the property statements)
ExampleCategory:Dutch politicians (Q7068416)Netherlands (Q55), politician (Q82955) and human (Q5)
Category:People from Lima (Q6062833)person, related to this place (Q19660746) and Lima (Q2868)
Category:2010 deaths (Q9707746)year of death (Q21160456) and 2010 (Q1995)
Category:1985 births (Q6647944)year of birth (Q21821348) and 1985 (Q2431)
Category:16th-century people (Q6824547)human (Q5) and 16th century (Q7017)
Category:Deaths in Los Angeles (Q9218950)place of death (Q18658526) and Los Angeles (Q65)
Category:20th century in the British Virgin Islands (Q8206289)20th century (Q6927) and British Virgin Islands (Q25305)
Robot and gadget jobsCheck constraints. Import these relations.
Tracking: local yes, WD nono label (Q32764977)
See alsocategory's main topic (P301), category contains (P4224)
Lists
Proposal discussionProperty proposal/Archive/15#P971
Current uses646,588
Search for values
[create] Create a translatable help page (preferably in English) for this property to be included here
Type “Wikimedia category (Q4167836): element must contain property “instance of (P31)” with classes “Wikimedia category (Q4167836)” or their subclasses (defined using subclass of (P279)). (Help)
List of this constraint violations: Database reports/Constraint violations/P971#Type Q4167836, hourly updated report, SPARQL, SPARQL (new)
Qualifiers “see also (P1659): this property should be used only with the listed qualifiers. (Help)
Exceptions are possible as rare values may exist.
List of this constraint violations: Database reports/Constraint violations/P971#Allowed qualifiers, SPARQL, SPARQL (new)
Conflicts with “subclass of (P279): this property must not be used with the listed properties and values. (Help)
Exceptions are possible as rare values may exist.
List of this constraint violations: Database reports/Constraint violations/P971#Conflicts with P279, search, SPARQL, SPARQL (new)
Multi value: this property generally contains two or more values. (Help)
Exceptions are possible as rare values may exist.
List of this constraint violations: Database reports/Constraint violations/P971#Multi value, SPARQL, SPARQL (new)
Conflicts with “instance of (P31): Wikimedia disambiguation category page (Q15407973): this property must not be used with the listed properties and values. (Help)
Exceptions are possible as rare values may exist.
List of this constraint violations: Database reports/Constraint violations/P971#Conflicts with P31, search, SPARQL, SPARQL (new)
Conflicts with “instance of (P31): Wikimedia list article (Q13406463): this property must not be used with the listed properties and values. (Help)
Exceptions are possible as rare values may exist.
List of this constraint violations: Database reports/Constraint violations/P971#Conflicts with P31, search, SPARQL, SPARQL (new)
Pictogram voting comment.svg Values shouldn't be the same for P301 and P971
to do: remove it from either category's main topic (P301) or category combines topics (P971) (Help)
Violations query: SELECT ?item ?value { ?item wdt:P971 ?value . ?item wdt:P301 ?value . } LIMIT 500
List of this constraint violations: Database reports/Complex constraint violations/P971#Values shouldn't be the same for P301 and P971
If property value equals to film, by year of publication only (Q38078930) then claim category contains (P4224) = film (Q11424) will be created automatically.
Testing: TODO list

If property value equals to Wikimedia template (Q11266439) then claim category contains (P4224) = Wikimedia template (Q11266439) will be created automatically.
Testing: TODO list


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


Discussion[edit]

Single value[edit]

For single value (one-on-one mappings) use category's main topic (P301) (and topic's main category (P910) to link back). Multichill (talk) 10:40, 19 October 2013 (UTC)

Why only categories?[edit]

Why is this property restricted to categories? They are not the only pages combining topics. For instance, politics of the Netherlands (Q877631) combines Netherlands (Q55) and politics (Q7163), in much the same way as Category:Dutch politicians (Q7068416) combines Netherlands (Q55) and politician (Q82955). --Avenue (talk) 12:06, 26 October 2013 (UTC)

Symbol support vote.svg Support I second this. Furthermore, the main label should be "topic".

Eg I want to mark categories *and list pages* relevant to food and drink with category combines topics (P971) Europeana Food and Drink (Q19723898) but right now cannot do that. --Vladimir Alexiev (talk) 09:31, 1 April 2015 (UTC)

Nature of combination[edit]

Can we indicate the nature of the combination somehow, e.g. through qualifiers? It could be useful to distinguish between Category:American fiction (Q8245550) and Category:United States in fiction (Q8788365), for instance. --Avenue (talk) 12:38, 26 October 2013 (UTC)

We could add the something like the "see also" qualifier at Q8881537#P971. This could help working through lists like this. --- Jura 20:29, 12 November 2015 (UTC)
For lists like Wikidata:Database reports/items without claims categories/ltwiki this could be useful. --- Jura 23:06, 2 February 2016 (UTC)
Archived: Wikidata:Property_proposal/Archive/49#cct_applicable_property, existing qualifier should do.
--- Jura 10:05, 4 May 2016 (UTC)
See section #Qualifiers below, for proposal to use relation (P2309) rather than see also (P1659). I think it would be a lot more natural. Jheald (talk) 17:47, 1 February 2018 (UTC)

distinct values constraint (Q21502410)[edit]

I don't think category combines topics (P971)property constraint (P2302)  distinct values constraint (Q21502410) is true. --Mr. Ibrahem (talk) 20:19, 22 August 2017 (UTC)

I think so, but I wan to try it, if I found some merge candidates. JAn Dudík (talk) 05:11, 23 August 2017 (UTC)

I think we can try with sparql like

SELECT
?value
?item2Label ?item2
?itemLabel ?item

  		WHERE
  		{ 
  			?item wdt:P971 ?value .
          ?item2 wdt:P971 ?value .
		
  SERVICE wikibase:label { bd:serviceParam wikibase:language "ar,en". }
}

    	LIMIT 10

Mr. Ibrahem (talk) 00:11, 24 August 2017 (UTC)

Qualifiers[edit]

Two suggestions in relation to qualifiers:

Firstly, the property see also (P1659) seems particularly ill-suited and unintuitive to use for this. Would anyone object if we changed to use relation (P2309) instead? The semantics here would exactly parallel its use for constraints. In each case, its meaning as a qualifier would be to indicate the property required to join an item to the value of the main statement in order for a requirement to be met -- in the case of a constraint, the test for the constraint to be satisfied; here the part of the test for an item to be a member of the category.

Secondly, can I suggest that it would be useful to be able to capture a requirement that a statement might need to be qualified in some way to support category membership -- for example, perhaps a statement might have to have an end time (P582) or a particular end cause (P1534) to be appropriate. One great advantage of this property over category contains (P4224) is that this property has the potential to allow that. I suggest that it would be a very natural fit to allow such qualifiers here.

As a result, I think there is a case for dropping the current constraint on allowed qualifiers, to allow any qualifier to be included as part of the specification. Jheald (talk) 15:42, 1 February 2018 (UTC)

  • There is a proposal to replace "see also". Maybe you want to comment there. Would you have a sample for a use of P582 or P1534 ?
    --- Jura 15:46, 1 February 2018 (UTC)
@Jura1: An example of a category needing use of a qualifier for specification would be Category:Deputies of the 15th National Assembly of the French Fifth Republic (Q30230937), which could be specified:
category combines topics (P971)  human (Q5)
relation (P2309)  instance of (P31)
category combines topics (P971)  member of the French National Assembly (Q3044918)
relation (P2309)  position held (P39)
parliamentary term (P2937)  15th legislature of the Fifth French Republic (Q24939798)
(This example originally came up last year in the context of the UK parliament. The data structure there has since changed, to define each term as a separate position held. However the French politicians still uses the more condensed system).
Where was the proposal to replace "see also" ? Ah, I've found it now, further up the page. I'll add a note to 'see below'. Jheald (talk) 17:44, 1 February 2018 (UTC)
  • And for P582 or P1534 ? From my experience with cleaning up qualifiers, people mostly try to do with them what category contains (P4224) is meant to do.
    "relation" has (IMHO) the same problem as "property" discussed in the proposal: it was made for constraints. And also: it requires items, not properties as values.
    --- Jura 18:44, 1 February 2018 (UTC)
@Jura1: Hmm. You're right. :-(
Do we know why relation (P2309) is item-valued rather than property-valued? Were property-valued properties not available when it was proposed? Or is there some useful example of flexibility that was gained by making it item-valued? If it's the latter, then perhaps the same might be a reason to prefer something item-valued here.
I am not so worried about it having been made for constraints. If the same concept is useful here too, then it doesn't seem such a big deal to widen the properties it can be applied to. On the other hand, the properties it can take as values currently seem quite limited; I can see that that might make for valid objections to widening its domain, if that preserving that current restriction is useful in its present role.
As for examples using P582 or P1534, I thought I could come up with some -- eg particular categories of politicians who might have died in office, or resigned; or things that ceased to apply at a particular date -- but so far I haven't identified any. (Not that I have looked very much, they could well still be out there). Jheald (talk) 19:55, 2 February 2018 (UTC)