story: [Nancy] and her sister [Melissa] have never been close. Still, they love each other because they are family. [Otto] took his sister [Melissa] out to dinner for her birthday. [Nancy] has been waiting around all day for her son, [Robert].
query: ('Melissa', 'Robert')
clean_story: [Nancy] and her sister [Melissa] have never been close. Still, they love each other because they are family. [Nancy] has been waiting around all day for her son, [Robert].
proof_state: [{('Melissa', 'nephew', 'Robert'): [('Melissa', 'sister', 'Nancy'), ('Nancy', 'son', 'Robert')]}]