coll.intersection

flex.coll.intersection(list1, list2)

WITH [1, 2, 3, 4] AS a, [3, 4, 5, 6] AS b
RETURN flex.coll.intersection(a, b) AS result

result
-------
[3, 4]

MATCH (d1:Document {id: 'doc1'})
MATCH (d2:Document {id: 'doc2'})
WITH flex.coll.intersection(d1.tags, d2.tags) AS commonTags
WHERE size(commonTags) > 0
RETURN commonTags

MATCH (u1:User {id: $userId1})
MATCH (u2:User {id: $userId2})
WITH flex.coll.intersection(u1.interests, u2.interests) AS sharedInterests
RETURN u1.name, u2.name, sharedInterests, size(sharedInterests) AS commonCount

WITH ['admin', 'read', 'write', 'delete'] AS allowed
MATCH (u:User)
WITH u, flex.coll.intersection(u.permissions, allowed) AS validPerms
RETURN u.name, validPerms