从SPARQL中的计数获取最大结果

我有一个疑问：

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX curricula: <http://www.semanticweb.org/lsarni/ontologies/curricula#>
SELECT ?topic (COUNT(?x) as ?number_of_courses)
WHERE {
   ?topic curricula:taughtIn ?x .
}
GROUP BY ?topic
ORDER BY desc(?number_of_courses)

这将返回：

但是我无法获得

？主题

我怎样才能解决这个问题


更新
我尝试了我从AKSW评论中理解的内容：

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX curricula: <http://www.semanticweb.org/lsarni/ontologies/curricula#>
SELECT ?topic 
WHERE { 
  ?topic curricula:taughtIn ?x . 
  { 
    SELECT (MAX(?number_of_courses) AS ?max) 
    WHERE { 
      { 
        SELECT ?topic (COUNT(?x) as ?number_of_courses) 
        WHERE { 
           ?topic curricula:taughtIn ?x . 
         } 
         GROUP BY ?topic 
      }
    } 
  }
} 
GROUP BY ?topic
HAVING (COUNT(?x) = ?max)

一个外部查询与最内部的查询相同，并结合
HAVING（COUNT（？x）=？max）
应该可以做到这一点。
SELECT？topic WHERE{？topic courses:taughtIn？x.{SELECT（max（？number____课程）as？max）WHERE{SELECT？topic topic（COUNT（？x）as？number______课程）WHERE{topic topic topic courseum:taughtIn？x.}GROUP BY？topic}}}}GROUP BY？topic具有（COUNT（？x）=？max）
您是否有一些示例数据供我在本地检查？我可能错了，这就是为什么建议提供一个最小的样本数据集，这样这里的人就可以验证他们建议的方法。好吧，事实上我错了，我忘记了加入我的建议。我想一个解决方案（虽然可能不是最有效的方法）是再次执行内部子查询并对count变量执行联接：
SELECT？topic WHERE{{SELECT？topic（count（？x）as？count）WHERE{topic coursessions:taughtIn？x.}GROUP BY？topic}{SELECT（MAX（？number of_of_courses）as？count WHERE{{SELECT？topic（将（？x）计算为？课程数）其中{主题课程：taughtIn？x.}按？主题}}}分组
@AKSW该选项有效！谢谢！请将其作为答案，以便我选择正确的选项
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX curricula: <http://www.semanticweb.org/lsarni/ontologies/curricula#>
SELECT ?topic 
WHERE { 
  ?topic curricula:taughtIn ?x . 
  { 
    SELECT (MAX(?number_of_courses) AS ?max) 
    WHERE { 
      { 
        SELECT ?topic (COUNT(?x) as ?number_of_courses) 
        WHERE { 
           ?topic curricula:taughtIn ?x . 
         } 
         GROUP BY ?topic 
      }
    } 
  }
} 
GROUP BY ?topic
HAVING (COUNT(?x) = ?max)

@prefix : <http://www.semanticweb.org/lsarni/ontologies/curricula#> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix xml: <http://www.w3.org/XML/1998/namespace> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@base <http://www.semanticweb.org/lsarni/ontologies/curricula> .

<http://www.semanticweb.org/lsarni/ontologies/curricula> rdf:type owl:Ontology .

#################################################################
#    Object Properties
#################################################################

###  http://www.semanticweb.org/lsarni/ontologies/curricula#taughtIn
:taughtIn rdf:type owl:ObjectProperty ;
          rdfs:subPropertyOf owl:topObjectProperty .


###  http://www.w3.org/2002/07/owl#topObjectProperty
owl:topObjectProperty rdfs:domain :Topic ;
                      rdfs:range :Course .


#################################################################
#    Classes
#################################################################

###  http://www.semanticweb.org/lsarni/ontologies/curricula#Course
:Course rdf:type owl:Class ;
        owl:disjointWith :Topic .


###  http://www.semanticweb.org/lsarni/ontologies/curricula#Topic
:Topic rdf:type owl:Class .


#################################################################
#    Individuals
#################################################################

###  http://www.semanticweb.org/lsarni/ontologies/curricula#Course_1
:Course_1 rdf:type owl:NamedIndividual ,
                   :Course .


###  http://www.semanticweb.org/lsarni/ontologies/curricula#Course_2
:Course_2 rdf:type owl:NamedIndividual ,
                   :Course .


###  http://www.semanticweb.org/lsarni/ontologies/curricula#Topic_1
:Topic_1 rdf:type owl:NamedIndividual ,
                  :Topic ;
         :taughtIn :Course_1 .


###  http://www.semanticweb.org/lsarni/ontologies/curricula#Topic_2
:Topic_2 rdf:type owl:NamedIndividual ,
                  :Topic ;
         :taughtIn :Course_1 ,
                   :Course_2 .


###  Generated by the OWL API (version 4.2.8.20170104-2310) https://github.com/owlcs/owlapi