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: Robert is a sailor if and only if it is snowing. Robert is a sailor. Jessica is a doctor if and only if it is snowing.
If Robert were a sailor, then it is snowing can be inferred via the biconditional elimination rule. If Jessica were a doctor, then it is snowing can be inferred via the biconditional elimination rule. If it snows, then Robert is a sailor can be inferred via the biconditional elimination rule. If it snows, then Jessica is a doctor can be inferred via the biconditional elimination rule.