[Wesley] bought a book for his son [Irvin]. [Pamela] needed to go to the store. [Pamela] asked her sister [Mildred] for a ride. [Pamela] was playing in the sandbox with her brother [Irvin].
('Mildred', 'Wesley')
[Pamela] needed to go to the store. [Pamela] asked her sister [Mildred] for a ride. [Pamela] was playing in the sandbox with her brother [Irvin]. [Wesley] bought a book for his son [Irvin].
[{('Mildred', 'father', 'Wesley'): [('Mildred', 'brother', 'Irvin'), ('Irvin', 'father', 'Wesley')]}, {('Mildred', 'brother', 'Irvin'): [('Mildred', 'sister', 'Pamela'), ('Pamela', 'brother', 'Irvin')]}]
['sister', 'brother', 'father']