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 is not a police officer. There is at least one x_7 for which x_7 is a police officer if and only if x_7 will sleep. For all x_7, x_7 is not an astronaut or x_7 is an artist. For all x_7, x_7 is an astronaut or x_7 will sleep.
For all x_7, x_7 will sleep or x_7 is an artist can be inferred via the universal resolution rule. There is at least one x_7 for which if x_7 were a police officer, then x_7 is sleeping can be inferred via the existential biconditional elimination rule. There is at least one x_7 for which if x_7 sleeps, then x_7 is a police officer can be inferred via the existential biconditional elimination rule. There is at least one x_7 for which x_7 will not sleep can be inferred via the existential biconditional elimination rule.