I have a database formatted like this:

(a:Concept)-[r:BROADER_TERM]->(b:Concept)-[s:BROADER_TERM]->(c:Concept)-[t:RELATED_TERM]->(d:Concept)

I’d like to write a query that returns Concept nodes that only have incoming BROADER_TERM edges and excludes any node that has both incoming and outgoing BROADER_TERM edges (ie I want to return the ‘broadest term’). In the example above, it would be a query that only returns node c.

I tried something like this:

MATCH (a:Concept)-[r:BROADER_TERM]->(b)
WHERE NOT (b)-[r]->(c:Concept)
RETURN b

But I can’t introduce a new variable in the WHERE NOT clause.

Can someone show me the correct syntax for this type of query?