[Robert] made a grilled cheese for his son [Mario]. [Mario]'s brother [Allan] ate a salad. [Angelica] and her brother [Ronald] watched TV together. [Allan] was invited to watch too, because [Angelica] is his sister.
('Robert', 'Ronald')
[Robert] made a grilled cheese for his son [Mario]. [Mario]'s brother [Allan] ate a salad. [Angelica] and her brother [Ronald] watched TV together. [Allan] was invited to watch too, because [Angelica] is his sister.
[{('Robert', 'son', 'Ronald'): [('Robert', 'son', 'Allan'), ('Allan', 'brother', 'Ronald')]}, {('Robert', 'son', 'Allan'): [('Robert', 'son', 'Mario'), ('Mario', 'brother', 'Allan')]}, {('Allan', 'brother', 'Ronald'): [('Allan', 'sister', 'Angelica'), ('Angelica', 'brother', 'Ronald')]}]
['son', 'brother', 'sister', 'brother']