[George] asked his father, [Clarence], to help him with his math homework. [Clarence] could n't, because he was lousy at math himself. [Dale] and his brother [George] are constantly trying to one up each other.
('Dale', 'Clarence')
[Dale] and his brother [George] are constantly trying to one up each other. [George] asked his father, [Clarence], to help him with his math homework. [Clarence] could n't, because he was lousy at math himself.
[{('Dale', 'father', 'Clarence'): [('Dale', 'brother', 'George'), ('George', 'father', 'Clarence')]}]
['brother', 'father']