Help:Property constraints portal/Symmetric

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symmetric constraint (Q21510862) specifies that a property is symmetric, and values for that property should have a statement with the same property pointing back to the original item.

For example, sibling (P3373) is symmetric: if the statement Lana Wachowski (Q9545711) sibling (P3373) Lilly Wachowski (Q9544977) exists, then the statement Lilly Wachowski (Q9544977) sibling (P3373) Lana Wachowski (Q9545711) should also exist. Other symmetric properties include spouse (P26), shares border with (P47), and twinned administrative body (P190).

If no constraint scope (P4680) is specified, this constraint is only checked on the main value of a statement. This is also the only currently supported scope.

Possible actionsEdit

There are several possible ways to address a violation of this constraint:

  • The most likely case is that the symmetric statement should be added to the other item, where it is missing.
  • It’s possible that the current item should not have the statement at all, and that the statement should be removed.
  • It’s possible that the item is a rare, but legitimate exception to the constraint, and nothing should be done.

ParametersEdit

This constraint does not have any parameters.

ExampleEdit

property constraint
  symmetric constraint
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add value

TemplateEdit

When the constraint is set to the property, the following template is automatically displayed in the property talk page. The template is created by Module:Constraints using Template:Constraint, invoked from Template:Property documentation. Translations are defined at Module:i18n/constraints.

 
Symmetric property: if [item A] has this property linked to [item B], then [item B] should also have this property linked to [item A]. (Help)
Exceptions are possible as rare values may exist.
List of this constraint violations: Database reports/Constraint violations/P3373#Symmetric, SPARQL, SPARQL (new)

ListsEdit

Lists of properties which are set symmetric constraint.