[Roberto] asked his father [Pedro] if they could go to the library. [Pedro]'s father [Harold] was there already, waiting for them. [Harold] made a sandwich for his son [Robert]. [Robert]'s brother [Antonio] ate an apple instead.
('Roberto', 'Antonio')
[Roberto] asked his father [Pedro] if they could go to the library. [Pedro]'s father [Harold] was there already, waiting for them. [Harold] made a sandwich for his son [Robert]. [Robert]'s brother [Antonio] ate an apple instead.
[{('Roberto', 'uncle', 'Antonio'): [('Roberto', 'father', 'Pedro'), ('Pedro', 'brother', 'Antonio')]}, {('Pedro', 'brother', 'Antonio'): [('Pedro', 'father', 'Harold'), ('Harold', 'son', 'Antonio')]}, {('Harold', 'son', 'Antonio'): [('Harold', 'son', 'Robert'), ('Robert', 'brother', 'Antonio')]}]
['father', 'father', 'son', 'brother']