What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_12, x_12 is a cashier if and only if x_12 is sad. For all x_12, if x_12 were a cashier, then x_12 is playing squash. For all x_12, x_12 is sad or x_12 will not play squash.
For all x_12, if x_12 plays squash, then x_12 is sad. For all x_12, if x_12 were a cashier, then x_12 is sad. For all x_12, if x_12 were sad, then x_12 is a cashier.