[Bobby]'s grandfather, [Harold], was part of a famous band. [Tracy] and her son [Bobby] went to the zoo with [Tracy]'s brother [Robert]. [Elsie] and her father [Robert] went to the park. They had a wonderful time there, feeding the ducks.
('Elsie', 'Harold')
[Elsie] and her father [Robert] went to the park. They had a wonderful time there, feeding the ducks. [Tracy] and her son [Bobby] went to the zoo with [Tracy]'s brother [Robert]. [Bobby]'s grandfather, [Harold], was part of a famous band.
[{('Elsie', 'grandfather', 'Harold'): [('Elsie', 'father', 'Robert'), ('Robert', 'father', 'Harold')]}, {('Robert', 'father', 'Harold'): [('Robert', 'sister', 'Tracy'), ('Tracy', 'father', 'Harold')]}, {('Tracy', 'father', 'Harold'): [('Tracy', 'son', 'Bobby'), ('Bobby', 'grandfather', 'Harold')]}]
['father', 'sister', 'son', 'grandfather']