[Robert] has a son named [Ronald] that looks exactly like him. [Robert]'s sister, [Dorothy], participated in the dance contest. [Marie] and her son [Ronald] went to the zoo and then out to dinner yesterday. [Tracy] took her sister [Dorothy] out for dinner to celebrate her birthday.
('Marie', 'Tracy')
[Marie] and her son [Ronald] went to the zoo and then out to dinner yesterday. [Robert] has a son named [Ronald] that looks exactly like him. [Robert]'s sister, [Dorothy], participated in the dance contest. [Tracy] took her sister [Dorothy] out for dinner to celebrate her birthday.
[{('Marie', 'sister', 'Tracy'): [('Marie', 'son', 'Ronald'), ('Ronald', 'aunt', 'Tracy')]}, {('Ronald', 'aunt', 'Tracy'): [('Ronald', 'father', 'Robert'), ('Robert', 'sister', 'Tracy')]}, {('Robert', 'sister', 'Tracy'): [('Robert', 'sister', 'Dorothy'), ('Dorothy', 'sister', 'Tracy')]}]
['son', 'father', 'sister', 'sister']