@prefix log: <http://www.w3.org/2000/10/swap/log#>.
@prefix : <http://example.org/ns#>.

:Ghent a :City.

(_:x) log:onNegativeSurface {
    _:x a :City.
    () log:onNegativeSurface {
        _:x a :HumanCommunity.
    }.
}.

# query
(_:S _:C) log:onQuerySurface {
    _:S a _:C.
}.
