[Douglas] gave his mother [Lillian] flowers on her birthday. [Jerry] loved his mother, [Lillian].
('Douglas', 'Jerry')
[Douglas] gave his mother [Lillian] flowers on her birthday. [Jerry] loved his mother, [Lillian].
[{('Douglas', 'brother', 'Jerry'): [('Douglas', 'mother', 'Lillian'), ('Lillian', 'son', 'Jerry')]}]
['mother', 'son']