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: There is at least one x_15 for which x_15 is a janitor if and only if x_15 is curious. For all x_15, if x_15 were a server, then x_15 is a scientist. For all x_15, x_15 is a server. For all x_15, x_15 is curious or x_15 is not a scientist.
For all x_15, x_15 is a scientist can be inferred via the universal modus ponens rule. For all x_15, if x_15 were a scientist, then x_15 is curious can be inferred via the universal rewriting rule. There is at least one x_15 for which if x_15 were a janitor, then x_15 is curious can be inferred via the existential biconditional elimination rule. There is at least one x_15 for which if x_15 were curious, then x_15 is a janitor can be inferred via the existential biconditional elimination rule.