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 sleep if and only if x_7 will work. For all x_7, x_7 is not fast or x_7 will work. For all x_7, if x_7 listens to a song, then x_7 is sleeping. There is at least one x_7 for which x_7 is fast or x_7 will listen to a song.
There is at least one x_7 for which x_7 will listen to a song or x_7 will work can be inferred via the existential resolution rule. For all x_7, if x_7 sleeps, then x_7 is working can be inferred via the universal biconditional elimination rule. For all x_7, if x_7 works, then x_7 is sleeping can be inferred via the universal biconditional elimination rule.