story: [Michelle] could n't pick up her son [Otto] at the airport. She decided to ask her daughter [Nancy] to do it. [Nancy]'s son, [Robert], was busy with school activities and forgot to meet his sister.
query: ('Nancy', 'Otto')
clean_story: [Michelle] could n't pick up her son [Otto] at the airport. She decided to ask her daughter [Nancy] to do it.
proof_state: [{('Nancy', 'brother', 'Otto'): [('Nancy', 'mother', 'Michelle'), ('Michelle', 'son', 'Otto')]}]