What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: If Robert climbs a mountain, then it is overcast. If Jennifer reads a book, then Robert is climbing a mountain. If it is overcast, then Jennifer is reading a book. If Jennifer reads a book, then it is overcast.
If Robert climbs a mountain, then Jennifer is reading a book can be inferred via the transitivity rule. If Jennifer reads a book, then it is overcast can be inferred via the transitivity rule. If it is overcast, then Robert is climbing a mountain can be inferred via the transitivity rule. It is overcast if and only if Jennifer is reading a book can be inferred via the biconditional introduction rule. Jennifer is reading a book if and only if it is overcast can be inferred via the biconditional introduction rule.