[Clarence] taught his daughter, [Amy], how to ride a bike. [Amy] bought her son [Michael] a basketball for his birthday.
('Michael', 'Clarence')
[Amy] bought her son [Michael] a basketball for his birthday. [Clarence] taught his daughter, [Amy], how to ride a bike.
[{('Michael', 'grandfather', 'Clarence'): [('Michael', 'mother', 'Amy'), ('Amy', 'father', 'Clarence')]}]
['mother', 'father']