Then, we filter out paths where (h, 1 , e) = (h, , t) or (e, 2 , t) = (h, , t), as well as the paths with 1 = 2 and h = e = t. We focused on "unambiguous" paths, so that the reasoning might actually make sense.
we considered only paths where 1 is either a 1-to-1 or a 1-to-many relationship, and where 2 is either a 1-to-1 or a many-to-1 relationship.