[Tracy] gave her brother [Robert] a new sweater for Christmas. [Dorothy] and her sister [Tracy] went to the basketball game. [Dorothy] invited [Louis] to meet them there, since she is his sister. [Robert] and his brother [Pedro] played at jacks.
('Louis', 'Pedro')
[Dorothy] and her sister [Tracy] went to the basketball game. [Dorothy] invited [Louis] to meet them there, since she is his sister. [Tracy] gave her brother [Robert] a new sweater for Christmas. [Robert] and his brother [Pedro] played at jacks.
[{('Louis', 'brother', 'Pedro'): [('Louis', 'sister', 'Tracy'), ('Tracy', 'brother', 'Pedro')]}, {('Louis', 'sister', 'Tracy'): [('Louis', 'sister', 'Dorothy'), ('Dorothy', 'sister', 'Tracy')]}, {('Tracy', 'brother', 'Pedro'): [('Tracy', 'brother', 'Robert'), ('Robert', 'brother', 'Pedro')]}]
['sister', 'sister', 'brother', 'brother']