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_8, x_8 is rich. There is at least one x_8 for which x_8 will listen to a song. For all x_8, x_8 is a server if and only if x_8 is rich.
There is at least one x_8 for which x_8 will listen to a song and x_8 is rich can be inferred via the existential conjunction rule. There is at least one x_8 for which x_8 is rich and x_8 will listen to a song can be inferred via the existential conjunction rule. For all x_8, if x_8 were a server, then x_8 is rich can be inferred via the universal biconditional elimination rule. For all x_8, if x_8 were rich, then x_8 is a server can be inferred via the universal biconditional elimination rule.