Works for SKOS files produced with Unilexicon and subset of Lexaurus export.
<rdf:RDF
xmlns:rdf="http://www.w3.org ... rdf-syntax-ns#"
xmlns:skos="http://www.w3.org/2004/02/skos/core#">
<skos:Concept rdf:about="...#mammals">
<skos:prefLabel>mammals</skos:prefLabel>
<skos:broader rdf:resource="...#animals"/>
</skos:Concept>
<skos:Concept rdf:about="..#animals">
<skos:prefLabel>animals</skos:prefLabel>
<skos:narrower rdf:resource="...#mammals"/>
</skos:Concept>
</rdf:RDF>