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 an artist or z is not a janitor. For all z, z will listen to a song. There is at least one z for which z is a janitor.
Some janitors will listen to a song can be inferred via the existential conjunction rule. There is at least one z for which z will listen to a song and z is a janitor can be inferred via the existential conjunction rule. For all z, if z were a janitor, then z is an artist can be inferred via the universal rewriting rule.