[Martha] and her sister [Lois] were going to the store to buy groceries. [Lois]'s mom, [Mary], called [Lois] to ask her to buy a gallon of milk.
('Mary', 'Martha')
[Martha] and her sister [Lois] were going to the store to buy groceries. [Lois]'s mom, [Mary], called [Lois] to ask her to buy a gallon of milk.
[{('Mary', 'daughter', 'Martha'): [('Mary', 'daughter', 'Lois'), ('Lois', 'sister', 'Martha')]}]