[Mario] asked his father, [Robert], to help him with his math homework. [Robert] could n't, because he was lousy at math himself. [Louis] was proud of his son, [Samuel]. [Robert] called his brother [Louis] on Friday because it was his birthday. [Samuel] went to visit his aunt [Dorothy] over the holiday and she gave him a present.
('Mario', 'Dorothy')
[Mario] asked his father, [Robert], to help him with his math homework. [Robert] could n't, because he was lousy at math himself. [Robert] called his brother [Louis] on Friday because it was his birthday. [Louis] was proud of his son, [Samuel]. [Samuel] went to visit his aunt [Dorothy] over the holiday and she gave him a present.
[{('Mario', 'aunt', 'Dorothy'): [('Mario', 'father', 'Robert'), ('Robert', 'sister', 'Dorothy')]}, {('Robert', 'sister', 'Dorothy'): [('Robert', 'brother', 'Louis'), ('Louis', 'sister', 'Dorothy')]}, {('Louis', 'sister', 'Dorothy'): [('Louis', 'son', 'Samuel'), ('Samuel', 'aunt', 'Dorothy')]}]
['father', 'brother', 'son', 'aunt']