story: [Erik] and his father [Peter] played video games all day last Saturday. [Erik] and his brother [Stacy] went to the arcade. They had a wonderful time. [Sandra] has a granddaughter called [Eustolia] who is her favourite. [Eustolia] and her brother [Erik] went to the movies together.
query: ('Stacy', 'Sandra')
clean_story: [Erik] and his brother [Stacy] went to the arcade. They had a wonderful time. [Eustolia] and her brother [Erik] went to the movies together. [Sandra] has a granddaughter called [Eustolia] who is her favourite.
proof_state: [{('Stacy', 'grandmother', 'Sandra'): [('Stacy', 'brother', 'Erik'), ('Erik', 'grandmother', 'Sandra')]}, {('Erik', 'grandmother', 'Sandra'): [('Erik', 'sister', 'Eustolia'), ('Eustolia', 'grandmother', 'Sandra')]}]