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 Elisabeth were a lawyer, then it is cold. If Elisabeth were a lawyer, then Susan is poor. If Susan were poor, then Elisabeth is a lawyer.
If Susan were poor, then it is cold can be inferred via the transitivity rule. Elisabeth is a lawyer if and only if Susan is poor can be inferred via the biconditional introduction rule. Susan is poor if and only if Elisabeth is a lawyer can be inferred via the biconditional introduction rule.