@prefix ex: <https://example.com/sets/query/> .
@prefix set: <https://ontology.inferal.com/modules/sets/> .

ex:s
    a set:Set ;
    set:hasMembership ex:s-a-left, ex:s-a-right .

ex:s-a-left
    a set:Membership ;
    set:inSet ex:s ;
    set:member ex:a .

ex:s-a-right
    a set:Membership ;
    set:inSet ex:s ;
    set:member ex:a .