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: For all y, y is a cashier. If Robert plays squash, then Robert is not a cashier. Patricia is a nurse if and only if Robert is not playing squash.
If Patricia were a nurse, then Robert is not playing squash can be inferred via the biconditional elimination rule. If Robert doesn't play squash, then Patricia is a nurse can be inferred via the biconditional elimination rule.