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[[Semantic MediaWiki]] includes an easy-to-use '''query language''' which enables users to access the wiki's knowledge. The syntax of this query language is very similar to the syntax of [[Help:annotation|annotations]] in Semantic MediaWiki. This query language can be used on the special page [[Special:Ask]] or in [[Help:inline queries|inline queries]].
<noinclude>{{Help contents back}}
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''This page has been copied from the Semantic MediaWiki web site at [http://ontoworld.org/wiki/Help:Semantic_search Ontoworld]. Please refer to that site for more detailed explanations and examples of Centiare's powerful semantic search facilities.''
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[http://meta.wikimedia.org/wiki/Semantic_MediaWiki Semantic MediaWiki] includes an easy-to-use '''query language''' which enables users to access the wiki's knowledge. The syntax of this query language is very similar to the syntax of [[Help:annotation|annotations]] in Semantic MediaWiki. This query language can be used on a [http://ontoworld.org/wiki/Special:Ask special page] (v0.6) or in [[Help:inline queries|inline queries]].
Naturally, answering queries requires additional resources, and the administrators of some sites can decide to switch off or restrict most of the features given below in order to ensure that even high-traffic sites can handle the additional load.
Naturally, answering queries requires additional resources, and the administrators of some sites can decide to switch off or restrict most of the features given below in order to ensure that even high-traffic sites can handle the additional load.
The following queries show what this means:
The following queries show what this means:
#<nowiki>[[Category:Actor]]</nowiki> gives all pages directly or indirectly (through a sub-, subsub-, etc. category) in the category.
#<nowiki>[[Category:Actor]]</nowiki> gives all pages directly or indirectly (through a sub-, subsub-, etc. category) in the category.
#<nowiki>[[born in::Boston]]</nowiki> gives all pages annotated as being about someone born in [[Boston]].
#<nowiki>[[born in::Boston]]</nowiki> gives all pages annotated as being about someone born in [[Directory:Boston|Boston]].
#<nowiki>[[height:=180cm]]</nowiki> gives all pages annotated as being about someone having a height of 180cm.
#<nowiki>[[height:=180cm]]</nowiki> gives all pages annotated as being about someone having a height of 180cm.
<nowiki><ask>[[Category:Actor]] [[born in::Boston]] [[height:=180cm]]</ask></nowiki>
<nowiki><ask>[[Category:Actor]] [[born in::Boston]] [[height:=180cm]]</ask></nowiki>
asks for everybody who is an actor ''and'' was born in Boston ''and'' is 180cm tall. In other words: when many conditions are written into one query, the result is narrowed down to those pages that meet all the requirements. Thus we have a [[wikipedia:Logical conjunction|logical AND]]. By the way: queries can also include line-breaks in order to make them more readable. So we could as well write:
asks for everybody who is an actor ''and'' was born in Boston ''and'' is 180cm tall. In other words: when many conditions are written into one query, the result is narrowed down to those pages that meet all the requirements. Thus we have a [[Centiare:Logical conjunction|logical AND]]. By the way: queries can also include line-breaks in order to make them more readable. So we could as well write:
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