Help:Property constraints portal/Symmetric
|This is the documentation page for a particular constraint type. See Help:Property constraints portal for a general overview of property constraints.|
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 exists, then the statement 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.
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.
This constraint does not have any parameters.
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)
Lists of properties which are set symmetric constraint.