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_7, x_7 will not work. For all x_7, if x_7 plays squash, then x_7 is a janitor. For all x_7, x_7 will play squash if and only if x_7 is bored. There is at least one x_7 for which if x_7 were a janitor, then x_7 is playing squash. For all x_7, if x_7 were bored, then x_7 is working.
For all x_7, x_7 is not bored can be inferred via the universal modus tollens rule. There is at least one x_7 for which x_7 is a janitor if and only if x_7 will play squash can be inferred via the existential biconditional introduction rule. There is at least one x_7 for which x_7 will play squash if and only if x_7 is a janitor can be inferred via the existential biconditional introduction rule. For all x_7, if x_7 plays squash, then x_7 is bored can be inferred via the universal biconditional elimination rule. For all x_7, if x_7 were bored, then x_7 is playing squash can be inferred via the universal biconditional elimination rule.