[Tracy] and [Robert] have a brother named [Pedro] [Pedro] made a sandwich for his son [Roberto]. [Roberto]'s brother [Jeffrey] ate an apple instead.
('Robert', 'Jeffrey')
[Tracy] and [Robert] have a brother named [Pedro] [Pedro] made a sandwich for his son [Roberto]. [Roberto]'s brother [Jeffrey] ate an apple instead.
[{('Robert', 'nephew', 'Jeffrey'): [('Robert', 'brother', 'Pedro'), ('Pedro', 'son', 'Jeffrey')]}, {('Robert', 'brother', 'Pedro'): [('Robert', 'sister', 'Tracy'), ('Tracy', 'brother', 'Pedro')]}, {('Pedro', 'son', 'Jeffrey'): [('Pedro', 'son', 'Roberto'), ('Roberto', 'brother', 'Jeffrey')]}]
['sister', 'brother', 'son', 'brother']