[Dale] and his son [Travis] went to the park and saw [Dale]'s father [Clarence] there with his dog.
('Travis', 'Clarence')
[Dale] and his son [Travis] went to the park and saw [Dale]'s father [Clarence] there with his dog.
[{('Travis', 'grandfather', 'Clarence'): [('Travis', 'father', 'Dale'), ('Dale', 'father', 'Clarence')]}]
['father', 'father']