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Help:Handling sitelinks overlapping multiple items
Ideas about how to handle sitelinks that overlap multiple concepts, from the Wikidata perspective. This issue is often referred to as the Bonnie and Clyde problem. This issue arises periodically, most often when editors new to Wikidata identify an issue local to their subject expertise.
Description of the problem
However, in some cases, a given Wikimedia site article describes multiple distinct but closely related concepts, such as:
- a team and its members, such as two people forming a duo (e.g. Bonnie Parker (Q2319886) and Clyde Barrow (Q3320282) forming Bonnie and Clyde (Q219937))
- an enterprise and its founder(s)
- a town and the island it is located on (that are named the same)
- a municipality and its capital city
- two objects systematically used together (e.g. mortar and pestle)
- subjects bundled into single articles because of semantic similarities in specific languages (e.g. "painters" create "paintings" using the manufacturing process of "painting")
- an enterprise and its founder(s)
- Various types of insurance (auto/boat/house) or government subsidies (unemployment/tax deductions/social security) or health subjects (broken leg/cast/bone setting)
- A general category (plates) and subcategories (disposable plates).
The difficulty is that specific Wikipedias may combine multiple items in a single article (e.g. Bonnie and Clyde (Q219937)), while other Wikipedias will have two articles to describe concepts separately (e.g. Bonnie Parker (Q2319886) and Clyde Barrow (Q3320282)).
Even if there is no disagreement between Wikipedias, there is no good way to link between part of a Wikipedia page that discusses an item (e.g., disposable plates) to a Wikidata item on it.
In the pre-Wikidata world before 2012, those Wikipedias containing a specific article on "Bonnie Parker" (i.e. pt:Bonnie Parker) could locally be linked either directly to a section of the "Bonnie AND Clyde" page on another Wikipedia (i.e. "en:Bonnie_and_Clyde#Bonnie_Parker") or they could be linked indirectly by a link pointing to a redirect page (e.g. Bonnie Parker) which then in turn points to the section of the article.
These interlanguage-links pointing to a section or an anchor (instead of to the article as a whole) are called "anchor links". They are still possible today (by adding a direct wiki-to-wiki link to to the wikitext source code of a page locally), and such links do not use Wikidata at all.
Such anchor links cannot be used as sitelinks on Wikidata, because even though the subjects may have separate items on Wikidata and be linked on Wikidata with various properties, e.g. Bonnie and Clyde (Q219937) has part (P527) Bonnie Parker (Q2319886), there is a hard limit on Wikidata to only have one sitelink per Wikipedia project per item. This is by design, because in the pre-Wikidata world, bots would struggle to update and "correct" circular references between various Wikipedia projects. Keeping the unique "one sitelink per Wikipedia page" relationship solves that problem, which resulted in many unnecessary edits and confusing error messages.
Note that is perfectly fine to create a Wikidata item for an anchor-linked topic on Wikipedia, even though it is not possible to create a sitelink to that anchor-link from the item. Just make sure that the item is linked to the parent item as described below (e.g. with the "part of (P361)" relationship).
Wikidata handling until a better solution is identified
A general agreement, respecting Wikidata ontology, is that Wikidata should hold one item for each individual page on Wikipedia, which may include one item representing the combined entity (such as Bonnie Parker (Q2319886), Clyde Barrow (Q3320282) and Bonnie and Clyde (Q219937)). Sitelinks of different language wikipedias should be associated to the item matching the best choice of the concept of each article.
Note that not all items need to have a Wikipedia page.
- Has part
- Bonnie and Clyde (Q219937) has part (P527) Bonnie Parker (Q2319886) and Clyde Barrow (Q3320282)
- Bonnie Parker (Q2319886) part of (P361) Bonnie and Clyde (Q219937)
- Clyde Barrow (Q3320282) part of (P361) Bonnie and Clyde (Q219937)
- Subclass of
- "Depicts" vs. "Based on" vs. "Different from"
- An artwork might be a copy of another artwork, in which case it depicts (P180) that original artwork and if it is not a 1-1 relationship such as a specific documented copy, then it is different from (P1889) all of the other items that it may or may not be an exact copy of.
- If not a copy, an artwork can be based on (P144) another artwork, and otherwise it depicts (P180) smething specific, such as a popular sculpture, painting, engraving, a scene from a poem, book, or play.
Other relations, such as located in the administrative territorial entity (P131), might better fit different concepts.
In many problematic cases where different Wikipedias handle such concepts differently, there will often already be existing redirects from the individuals to the group, or to subsections of it.
One possibility for restoring interwiki sitelinks is to link WD items representing individual concepts to WP redirect pages (such as Bonnie Parker (Q2319886) associated to en:Bonnie Parker). However, since Wikidata software (as of April 2015) automatically follows the WP redirect to the target page when an attempt is made to associate a redirect to a Wikidata item, it is not straightforward to create such an association.
Here is the procedure if you are nonetheless willing to associate a WD item to a WP redirect:
- Access the WP redirect page
- Temporarily deactivate the redirection and save
- Associate the WD item to the WP (disabled) redirect
- Revert the WP redirect page back to its original state
Most existing sitelinks to Wikipedia redirects are unintentional left-overs caused by an article merge on Wikipedia, for which no corresponding item merge was done on Wikidata. Most sitelinks to redirects therefore signal a data problem on Wikidata that remains to be addressed (ie a duplicate item).
To signal that your sitelink to a redirect is intentional, and not just an accidental left-over, on many wikipedias a local version of Template:Wikidata redirect (Q16956589) exists to allow this to be indicated. This should be added to the redirect page, if the template is available.
Adding interwikis locally
If some Wikipedia language versions decide that specific pages should lead to another page at another Wikipedia, this can be done by placing "old style" interwikis on the page.
To use infoboxes in articles articles combining information from several Wikidata items, one would need to specify the Wikidata item(s) explicitly.
- To use fr:Template:Infobox Biographie2 on fr:Bonnie et Clyde (Q219937), for each of them, one would use:
Discuss the solutions
A WikiProject is dedicated to the compilation of all related problems and to discussion of potential solutions on the broader problem of interwikis hard to handle : WD:XLINK.
There is also a current "Request for comment" to allow the creation of links to redirects.
And, there's a goal task, though stalled, that tries to decrease the "only one link per sites in one item" limitation so that Incubator support would be possible.
- Information on identifying and handling Interwiki conflicts on Meta.Wikimedia.org
- Wikidata:Requests for comment/Allow the creation of links to redirects in Wikidata - Further discussion of changes to Wikidata to improve Wikidata's handling of this issue