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 it snows, then Robert is a carpenter. If Jessica were an office clerk, then Robert is a carpenter. If it is windy, then it is snowing. If Robert were a carpenter, then Jessica is an office clerk.
If it snows, then Jessica is an office clerk can be inferred via the transitivity rule. If it is windy, then Robert is a carpenter can be inferred via the transitivity rule. Jessica is an office clerk if and only if Robert is a carpenter can be inferred via the biconditional introduction rule. Robert is a carpenter if and only if Jessica is an office clerk can be inferred via the biconditional introduction rule.