@prefix : <http://example.org/#>.

# Modus tollens example.
# If X is a chicken, then X is a bird
{
    ?X a :Chicken.
} => {
    ?X a :Bird.
}.

# Rex is not a bird...
{
    :Rex a :Bird.
} => ($ $).

# ..then Rex is not a chicken
# query
{
    {
        :Rex a ?O
    } => ($ $).
} =^ {
    {
        :Rex a ?O
    } => ($ $).
}.
