story: [Robert] and his brother [Chad] went to the park to play basketball. [Jason] is the proud grandfather of [Robert].
query: ('Jason', 'Chad')
clean_story: [Jason] is the proud grandfather of [Robert]. [Robert] and his brother [Chad] went to the park to play basketball.
proof_state: [{('Jason', 'grandson', 'Chad'): [('Jason', 'grandson', 'Robert'), ('Robert', 'brother', 'Chad')]}]
edge_types: ['grandson', 'brother']