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: If Barbara sleeps, then James is a janitor. For all x_15, x_15 will listen to a song if and only if x_15 will sleep. If James were a janitor, then Barbara is listening to a song.
If Barbara sleeps, then Barbara is listening to a song can be inferred via the transitivity rule. For all x_15, if x_15 listens to a song, then x_15 is sleeping can be inferred via the universal biconditional elimination rule. For all x_15, if x_15 sleeps, then x_15 is listening to a song can be inferred via the universal biconditional elimination rule.