[Jacob] and his mother, [Nancy], went to the movie theater. [Nancy]'s father, [Clarence], met them there.
('Jacob', 'Clarence')
[Jacob] and his mother, [Nancy], went to the movie theater. [Nancy]'s father, [Clarence], met them there.
[{('Jacob', 'grandfather', 'Clarence'): [('Jacob', 'mother', 'Nancy'), ('Nancy', 'father', 'Clarence')]}]
['mother', 'father']