SPARQL 1.1中属性路径的筛选器

有什么方法可以过滤像这样的查询吗

选择？x？y，其中{x+？y}”；

对于提供的数据集，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，这样我们就可以删除另一个结果中具有？x值等于？y值的所有结果

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值出现在其他结果中

以下是数据集：

<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> .

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选择？x？y，其中{x+？y}

我们如何过滤查询，以便使用 在另一个结果中等于？y值的？x值

如果一行中的？x值是另一行中的？y值，则意味着？x是wasRevisionOf属性上某个三元组的对象。您可以简单地将其过滤掉：

选择？x？y，其中{
？x+？y
筛选器不存在{
什么
}
}

这确保？x的每个值都是链的“起点”

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