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 is cold, then Robert is not playing tennis. It is cold if and only if Patricia is a nurse. Robert is playing tennis.
It is not cold can be inferred via the modus tollens rule. If it is cold, then Patricia is a nurse can be inferred via the biconditional elimination rule. If Patricia were a nurse, then it is cold can be inferred via the biconditional elimination rule.