[Louis] and his brother [Robert] went fishing but [Louis] did n't invite his other brother [Antonio]. [Robert] loved teaching his son, [Ronald], baseball. [Ronald] went fishing with his uncle [Pedro].
('Antonio', 'Pedro')
[Louis] and his brother [Robert] went fishing but [Louis] did n't invite his other brother [Antonio]. [Robert] loved teaching his son, [Ronald], baseball. [Ronald] went fishing with his uncle [Pedro].
[{('Antonio', 'brother', 'Pedro'): [('Antonio', 'brother', 'Louis'), ('Louis', 'brother', 'Pedro')]}, {('Louis', 'brother', 'Pedro'): [('Louis', 'brother', 'Robert'), ('Robert', 'brother', 'Pedro')]}, {('Robert', 'brother', 'Pedro'): [('Robert', 'son', 'Ronald'), ('Ronald', 'uncle', 'Pedro')]}]
['brother', 'brother', 'son', 'uncle']