[Robert] bought a book for his father [Wayne]. [Clarence] took his grandson [Robert] to the store to buy some new books.
('Wayne', 'Clarence')
[Robert] bought a book for his father [Wayne]. [Clarence] took his grandson [Robert] to the store to buy some new books.
[{('Wayne', 'father', 'Clarence'): [('Wayne', 'son', 'Robert'), ('Robert', 'grandfather', 'Clarence')]}]
['son', 'grandfather']