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: Jessica is a soldier or Joseph is a doctor. For all x_7, x_7 is a soldier if and only if x_7 is a cashier. If Joseph were a doctor, then Jessica is a cashier.
For all x_7, if x_7 were a soldier, then x_7 is a cashier can be inferred via the universal biconditional elimination rule. For all x_7, if x_7 were a cashier, then x_7 is a soldier can be inferred via the universal biconditional elimination rule.