SPARQL 1.1 中的属性路径过滤器答案

【问题标题】：Filter for property path in SPARQL 1.1SPARQL 1.1 中的属性路径过滤器
【发布时间】：2016-05-10 15:54:29
【问题描述】：

有没有办法过滤像

这样的查询

select ?x ?y  where {?x <http://relationship.com/wasRevisionOf>+ ?y }";

提供的数据集具有以下输出：

http://article.com/2-3 http://article.com/2-2
http://article.com/2-3 http://article.com/2-1
http://article.com/2-4 http://article.com/2-3
http://article.com/2-4 http://article.com/2-2
http://article.com/2-4 http://article.com/2-1
http://article.com/2-2 http://article.com/2-1
http://article.com/1-3 http://article.com/1-2
http://article.com/1-3 http://article.com/1-1
http://article.com/1-2 http://article.com/1-1

我们如何过滤查询，以便我们删除所有 ?x 值等于另一个结果中的 ?y 值的结果。这样，我们将得到

http://article.com/2-4 http://article.com/2-3
http://article.com/2-4 http://article.com/2-2
http://article.com/2-4 http://article.com/2-1

因为所有其他结果的 ?x 值作为 ?y 值出现在另一个结果中。

这是数据集：

<http://article.com/1-3> <http://relationship.com/wasGeneratedBy> <http://edit.com/comment1-2> .
<http://article.com/1-3> <http://relationship.com/wasRevisionOf> <http://article.com/1-2> .
<http://edit.com/comment1-2> <http://relationship.com/used> <http://article.com/1-2> .
<http://edit.com/comment1-2> <http://relationship.com/wasAssociatedWith> <http://editor.com/user1-1> .

<http://article.com/1-2> <http://relationship.com/wasGeneratedBy> <http://edit.com/comment1-1> .
<http://article.com/1-2> <http://relationship.com/wasRevisionOf> <http://article.com/1-1> .
<http://edit.com/comment1-1> <http://relationship.com/used> <http://article.com/1-1> .
<http://edit.com/comment1-1> <http://relationship.com/wasAssociatedWith> <http://editor.com/user1-1> .

<http://article.com/2-4> <http://relationship.com/wasGeneratedBy> <http://edit.com/comment2-3> .
<http://article.com/2-4> <http://relationship.com/wasRevisionOf> <http://article.com/2-3> .
<http://edit.com/comment2-3> <http://relationship.com/used> <http://article.com/2-3> .
<http://edit.com/comment2-3> <http://relationship.com/wasAssociatedWith> <http://editor.com/user2-3> .

<http://article.com/2-3> <http://relationship.com/wasGeneratedBy> <http://edit.com/comment2-2> .
<http://article.com/2-3> <http://relationship.com/wasRevisionOf> <http://article.com/2-2> .
<http://edit.com/comment2-2> <http://relationship.com/used> <http://article.com/2-2> .
<http://edit.com/comment2-2> <http://relationship.com/wasAssociatedWith> <http://editor.com/user2-2> .

<http://article.com/2-2> <http://relationship.com/wasGeneratedBy> <http://edit.com/comment2-1> .
<http://article.com/2-2> <http://relationship.com/wasRevisionOf> <http://article.com/2-1> .
<http://edit.com/comment2-1> <http://relationship.com/used> <http://article.com/2-1> .
<http://edit.com/comment2-1> <http://relationship.com/wasAssociatedWith> <http://editor.com/user2-1> .

【问题讨论】：

标签： sparql rdf semantic-web triplestore propertypath

【解决方案1】：

select ?x ?y  where {?x <http://relationship.com/wasRevisionOf>+ ?y }
我们如何过滤查询，以便我们删除所有结果一个 ?x 值等于另一个结果中的一个 ?y 值。

如果某一行中的 ?x 值是另一行中的 ?y 值，则意味着存在 ?x 是 wasRevisionOf 属性上某个三元组的对象。您可以简单地将它们过滤掉：

select ?x ?y  where {
  ?x <http://relationship.com/wasRevisionOf>+ ?y
  filter not exists {
    ?something <http://relationship.com/wasRevisionOf> ?x
  }
}

这确保 ?x 的每个值都是链的“开始”。

【讨论】：