story: [Ellen] and her father [Otto] went to visit his sister [Crystal]. [Otto] 'son [William] could not believe that his father bought him a coffee machine for his birthday.
query: ('Crystal', 'Ellen')
clean_story: [Ellen] and her father [Otto] went to visit his sister [Crystal].
proof_state: [{('Crystal', 'niece', 'Ellen'): [('Crystal', 'brother', 'Otto'), ('Otto', 'daughter', 'Ellen')]}]