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_12, x_12 is an artist if and only if x_12 will work. William is making tea or Barbara is not an artist. William is not making tea.
Barbara is not an artist can be inferred via the disjunctive syllogism rule. If Barbara were an artist, then William is making tea can be inferred via the rewriting rule. For all x_12, if x_12 were an artist, then x_12 is working can be inferred via the universal biconditional elimination rule. For all x_12, if x_12 works, then x_12 is an artist can be inferred via the universal biconditional elimination rule.