测试不存在匹配它的模式 returns 个三元组

Question

为什么此查询的第一个结果与两个缺席测试匹配，而页面上显示的是值？

#Leaders of Member states of the EU for which there is no value for gender or depiction in DBpedia

SELECT DISTINCT ?leader_No_gender ?leader_No_image

WHERE { 
?MS a dbo:Country; dct:subject <http://dbpedia.org/resource/Category:Member_states_of_the_European_Union>. 

{?MS dbo:leader ?leader_No_gender . 
FILTER NOT EXISTS {?leader_No_gender foaf:gender ?gender}
} 

UNION 

{?MS dbo:leader ?leader_No_image . 
FILTER NOT EXISTS {?leader_No_image foaf:depiction ?image}
} 
}

Answer 1

property path-based queries suggested by @AKSW work on the latest Virtuoso Enterprise Edition (08.03.3312) 主持DBpedia-Live。（当然，这些结果不同于您在静态 DBpedia 上找到的结果，它仍然基于 2016-10 数据集，并且仍然运行在 Virtuoso 07.20.3230 上仍然有属性路径错误。）

PREFIX dbo: <http://dbpedia.org/ontology/>
PREFIX dct: <http://purl.org/dc/terms/>

SELECT DISTINCT 
  ?leader_No_gender 
  ?leader_No_image

WHERE 
  { 
    ?MS a           dbo:Country ; 
        dct:subject <http://dbpedia.org/resource/Category:Member_states_of_the_European_Union> . 

    { ?MS dbo:leader ?leader_No_gender . 
      FILTER NOT EXISTS { ?leader_No_gender dbo:wikiPageRedirects?/foaf:gender ?gender }
    } 

    UNION

    { ?MS dbo:leader ?leader_No_image . 
      FILTER NOT EXISTS { ?leader_No_image dbo:wikiPageRedirects?/foaf:depiction ?image }
    }
  }

测试不存在匹配它的模式 returns 个三元组

Test for absence of a pattern returns triples that match it

rdf

sparql

dbpedia