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_11, x_11 is happy or x_11 is rich. For all x_11, x_11 will listen to a song or x_11 is not rich. For all x_11, x_11 will listen to a song if and only if x_11 is happy.
For all x_11, if x_11 were rich, then x_11 is listening to a song can be inferred via the universal rewriting rule. For all x_11, if x_11 listens to a song, then x_11 is happy can be inferred via the universal biconditional elimination rule. For all x_11, if x_11 were happy, then x_11 is listening to a song can be inferred via the universal biconditional elimination rule.