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 z, z is a scientist or z will listen to a song. There is at least one z for which z is not a server. For all z, z is a server if and only if z is a scientist.
For all z, if z were a server, then z is a scientist can be inferred via the universal biconditional elimination rule. For all z, if z were a scientist, then z is a server can be inferred via the universal biconditional elimination rule. There is at least one z for which z is not a scientist can be inferred via the existential biconditional elimination rule.