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, if x were a police officer, then x is listening to a song. There is at least one x for which if x were a scientist, then x is listening to a song. For all x, x will listen to a song if and only if x is a police officer. For all x, x is a police officer or x is a scientist.
There is at least one x for which x will listen to a song can be inferred via the existential disjunction elimination rule. For all x, if x listens to a song, then x is a police officer can be inferred via the universal biconditional elimination rule. For all x, if x were a police officer, then x is listening to a song can be inferred via the universal biconditional elimination rule.