How to get resources not related by a property using sparql?

@herminia_bruen 

To get resources that are not related by a specific property using SPARQL, you can use optional patterns in your query. Optional patterns allow you to retrieve resources that may or may not have a specific property.

For example, if you want to retrieve all resources that are not related by the "hasSibling" property, you can use the following SPARQL query:

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SELECT ?resource
WHERE {
  ?resource a <http://example.org/Person> .
  OPTIONAL { ?resource <http://example.org/hasSibling> ?sibling . }
  FILTER (!bound(?sibling))
}

In this query, we first select all resources that are instances of the class "Person". We then use an OPTIONAL pattern to check if each resource has a sibling using the property "hasSibling". The FILTER statement checks if the variable ?sibling is not bound to any value, indicating that the resource does not have a sibling.

By using OPTIONAL patterns and FILTER statements in your SPARQL query, you can retrieve resources that are not related by a specific property.