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_12 for which x_12 will sleep. For all x_12, if x_12 reads a book, then x_12 is taking a plane. For all x_12, x_12 will read a book or x_12 is an artist. For all x_12, x_12 will climb a mountain if and only if x_12 will take a plane. For all x_12, if x_12 were an artist, then x_12 is taking a plane.
For all x_12, x_12 will take a plane can be inferred via the universal disjunction elimination rule. For all x_12, if x_12 climbs a mountain, then x_12 is taking a plane can be inferred via the universal biconditional elimination rule. For all x_12, if x_12 takes a plane, then x_12 is climbing a mountain can be inferred via the universal biconditional elimination rule.