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我正在尝试使用标识符的增量变量在图形上执行空白节点 skolemization，但是，urn:count 对象没有被更新。

到目前为止，我有以下代码。

PREFIX :    <http://example.com/>
PREFIX owl: <http://www.w3.org/2002/07/owl#>


####################
# Create Counter Graph #
####################

INSERT DATA {
    graph <urn:counters> {<urn:Example> <urn:count> 1 }
}
;


####################
# Rewrite objects #
####################

DELETE {
    #remove the old value of the counter
    graph <urn:counters> {<urn:Example> <urn:count> ?old}
  ?s ?p ?bnode .
}
INSERT {
    #update the new value of the counter
    graph <urn:counters> {<urn:Example> <urn:count> ?new}
  
  ?s ?p ?iri .
  GRAPH :aliases {
    ?bnode owl:sameAs ?iri .
  }
}
WHERE {
  {
    SELECT ?bnode ?iri ?new ?old
    WHERE {

      {        
        SELECT DISTINCT ?bnode
        WHERE {
          [] ?p ?bnode .
          FILTER isBlank(?bnode)
        }
      } 
                # retrieve the counter
    graph <urn:counters> {<urn:Example> <urn:count> ?old}
    
    
    # compute the new value
    bind(?old+1 as ?new)  
    
    
    #construct the IRI
    bind(IRI(concat("http://example.org/item/", str(?old))) as ?iri) 
    }
  }
    ?s ?p ?bnode .
}
;

这会产生以下输出。

<#TripleMap1>
        rr:logicalTable        <http://example.org/item/1> ;
        rr:predicateObjectMap  <http://example.org/item/1> ;
        rr:subjectMap          <http://example.org/item/1> .

但是我希望输出如下。

<#TripleMap1>
        rr:logicalTable        <http://example.org/item/1> ;
        rr:predicateObjectMap  <http://example.org/item/2> ;
        rr:subjectMap          <http://example.org/item/3> .

输入图如下。

@prefix rr:    <http://www.w3.org/ns/r2rml#> .
<#TripleMap1>
        rr:logicalTable        [] ;
        rr:predicateObjectMap  [];
        rr:subjectMap [];

任何帮助，将不胜感激。

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