snaf.trig

# --------------------------
# Scoped Negation As Failure
# --------------------------

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

# facts
:Alice :loves :Bob.
:Bob a :Person.

# rule
_:bng_1 log:implies _:bng_2.

_:bng_1 {
    var:SCOPE log:notIncludes _:bng_3.
    var:X a :Person.
}

_:bng_2 {
  :Alice :hates :Nobody.
}

_:bng_3 {
    :Alice :hates var:X.
}

# query
_:bng_4 log:query _:bng_4.

_:bng_4 {
    var:s :hates var:o.
}