[Robert] made a sandwich for his son [Mario]. [Mario]'s brother [Ronald] ate an apple instead. [Harold] is helping his son study. His name is [Pedro]. [Pedro] and his brother [Robert] were rarely seen apart.
('Harold', 'Ronald')
[Harold] is helping his son study. His name is [Pedro]. [Pedro] and his brother [Robert] were rarely seen apart. [Robert] made a sandwich for his son [Mario]. [Mario]'s brother [Ronald] ate an apple instead.
[{('Harold', 'grandson', 'Ronald'): [('Harold', 'grandson', 'Mario'), ('Mario', 'brother', 'Ronald')]}, {('Harold', 'grandson', 'Mario'): [('Harold', 'son', 'Robert'), ('Robert', 'son', 'Mario')]}, {('Harold', 'son', 'Robert'): [('Harold', 'son', 'Pedro'), ('Pedro', 'brother', 'Robert')]}]
['son', 'brother', 'son', 'brother']