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 curious or y is rich. For all y, if y were a nurse, then y is curious. For all y, if y were curious, then y is a nurse. There is at least one y for which y is not a nurse.
There is at least one y for which y is not curious can be inferred via the existential modus tollens rule. For all y, y is a nurse if and only if y is curious can be inferred via the universal biconditional introduction rule. For all y, y is curious if and only if y is a nurse can be inferred via the universal biconditional introduction rule.