[Martha] looked all over the house for her son [Adan], but could n't find him. That's because [Adan] was outside in the back yard, playing baseball with his brother [Robert].
('Robert', 'Martha')
[Martha] looked all over the house for her son [Adan], but could n't find him. That's because [Adan] was outside in the back yard, playing baseball with his brother [Robert].
[{('Robert', 'mother', 'Martha'): [('Robert', 'brother', 'Adan'), ('Adan', 'mother', 'Martha')]}]