[Dale] made a sandwich for his son [Travis]. [Travis]'s brother [Tony] ate an apple instead.
('Dale', 'Tony')
[Dale] made a sandwich for his son [Travis]. [Travis]'s brother [Tony] ate an apple instead.
[{('Dale', 'son', 'Tony'): [('Dale', 'son', 'Travis'), ('Travis', 'brother', 'Tony')]}]
['son', 'brother']