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 x_11, x_11 will work if and only if x_11 is poor. For all x_11, if x_11 works, then x_11 is not taking a plane. For all x_11, x_11 will take a plane and x_11 will sleep. There is at least one x_11 for which x_11 is poor if and only if x_11 is a server.
For all x_11, x_11 will take a plane can be inferred via the universal simplification rule. For all x_11, x_11 will sleep can be inferred via the universal simplification rule. For all x_11, if x_11 works, then x_11 is poor can be inferred via the universal biconditional elimination rule. There is at least one x_11 for which if x_11 were poor, then x_11 is a server can be inferred via the existential biconditional elimination rule. For all x_11, if x_11 were poor, then x_11 is working can be inferred via the universal biconditional elimination rule. There is at least one x_11 for which if x_11 were a server, then x_11 is poor can be inferred via the existential biconditional elimination rule.