<http://dbpedia.org/resource/Relation_algebra>	<http://www.w3.org/2002/07/owl#differentFrom>	<http://dbpedia.org/resource/Relational_algebra> .
<http://dbpedia.org/resource/Relation_algebra>	<http://www.w3.org/2002/07/owl#differentFrom>	<http://dbpedia.org/resource/Relational_database> .
<http://dbpedia.org/resource/Relation_algebra>	<http://www.w3.org/2002/07/owl#differentFrom>	<http://dbpedia.org/resource/Finitary_relation> .
<http://dbpedia.org/resource/Relation_algebra>	<http://www.w3.org/2000/01/rdf-schema#comment>	"In mathematics and abstract algebra, a relation algebra is a residuated Boolean algebra expanded with an involution called converse, a unary operation."@en .