如何在Sparql中查询具有对象属性的类 [英] How to query Classes with Object Property in Sparql

问题描述

有人知道如何在Sparql中查询具有对象属性的类吗? 假设我们有一个包含以下内容的OWL文件

Does any one know how to query Classes with Object Property in Sparql? Assume we have an OWL file which contains follows

Human ----(hasPizza)---> Pizzas

人类和披萨是类(或概念).在SPARQL中，此查询不返回任何内容:

Human and Pizzas are classes (or concepts). In SPARQL, this query returns nothing:

select ?x ?y where {
  ?x hasPizza ?y
}

但是如果我在这些概念下添加两个人(或实体)

But if I add two individuals (or entities) under those concepts like

Human:Jim ----(hasPizza)---> Pizzas:cheesePizza

该查询将返回?x=Jim和?y=cheesePizza 如何使用SPARQL获得?x=Human和?y=Pizza?

that query will return ?x=Jim and ?y=cheesePizza How can I get ?x=Human and ?y=Pizza using SPARQL?

推荐答案

给出这样的数据(在RDF/XML中):

Given data like this (in RDF/XML):

<rdf:RDF
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:owl="http://www.w3.org/2002/07/owl#"
    xmlns:pizzas="http://example.org/pizzas#"
    xmlns:xsd="http://www.w3.org/2001/XMLSchema#"
    xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#">
  <owl:Ontology rdf:about="http://example.org/pizzas"/>
  <owl:Class rdf:about="http://example.org/pizzas#Pizza"/>
  <owl:Class rdf:about="http://example.org/pizzas#Human"/>
  <owl:ObjectProperty rdf:about="http://example.org/pizzas#hasPizza">
    <rdfs:domain rdf:resource="http://example.org/pizzas#Human"/>
    <rdfs:range rdf:resource="http://example.org/pizzas#Pizza"/>
  </owl:ObjectProperty>
  <owl:NamedIndividual rdf:about="http://example.org/pizzas#Jim">
    <rdf:type rdf:resource="http://example.org/pizzas#Human"/>
    <pizzas:hasPizza>
      <owl:NamedIndividual rdf:about="http://example.org/pizzas#CheesePizza">
        <rdf:type rdf:resource="http://example.org/pizzas#Pizza"/>
      </owl:NamedIndividual>
    </pizzas:hasPizza>
  </owl:NamedIndividual>
</rdf:RDF>

或相同，在更具可读性的Turtle中:

or the same, in the more readable Turtle:

@prefix :        <http://example.org/pizzas#> .
@prefix rdfs:    <http://www.w3.org/2000/01/rdf-schema#> .
@prefix pizzas:  <http://example.org/pizzas#> .
@prefix owl:     <http://www.w3.org/2002/07/owl#> .
@prefix xsd:     <http://www.w3.org/2001/XMLSchema#> .
@prefix rdf:     <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .

pizzas:Jim
      a       pizzas:Human , owl:NamedIndividual ;
      pizzas:hasPizza pizzas:CheesePizza .

pizzas:hasPizza
      a       owl:ObjectProperty ;
      rdfs:domain pizzas:Human ;
      rdfs:range pizzas:Pizza .

pizzas:Human
      a       owl:Class .

pizzas:Pizza
      a       owl:Class .

<http://example.org/pizzas>
      a       owl:Ontology .

pizzas:CheesePizza
      a       pizzas:Pizza , owl:NamedIndividual .

请注意，断言Jim hasPizza CheesePizza是图中的三分之一. hasPizza对象属性的域和范围公理是两个三元组:hasPizza rdfs:domain Human和hasPizza rdfs:range Pizza. SPARQL查询将查询模式与图中的三元组进行匹配.因此，通过类似这样的查询:

notice that the assertion Jim hasPizza CheesePizza is one triple in the graph. The domain and range axioms for the hasPizza object property are two triples: hasPizza rdfs:domain Human and hasPizza rdfs:range Pizza. SPARQL queries match query patterns against the triples in the graph. Thus, from a query like:

prefix :        <http://example.org/pizzas#>

select ?x ?y where { 
  ?x :hasPizza ?y
}

您将获得诸如

$ arq --data pizzas.ttl --query query.sparql
-----------------------
| x    | y            |
=======================
| :Jim | :CheesePizza |
-----------------------

因为图中有一个谓词为:hasPizza的三元组，并且该三元组以:Jim作为主语，而:CheesePizza作为对象.听起来您实际上是在要求:hasPizza属性的域和范围，它们也很容易检索.使用这样的查询:

because there is one triple in the graph whose predicate is :hasPizza, and that triple has a :Jim as the subject, and :CheesePizza as the object. It sounds like you're actually asking for the domain and range of the :hasPizza property, which are also easy to retrieve. Use a query like this:

prefix :        <http://example.org/pizzas#>
prefix rdfs:    <http://www.w3.org/2000/01/rdf-schema#>

select ?domain ?range where { 
  :hasPizza rdfs:domain ?domain ;
            rdfs:range ?range .
}

您将获得如下结果:

$ arq --data pizzas.ttl --query query.sparql
-------------------
| domain | range  |
===================
| :Human | :Pizza |
-------------------

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