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_11, x_11 will sleep if and only if x_11 is excited. There is at least one x_11 for which if x_11 climbs a mountain, then x_11 is excited. For all x_11, x_11 will climb a mountain or x_11 will not sleep.
For all x_11, if x_11 sleeps, then x_11 is climbing a mountain can be inferred via the universal rewriting rule. For all x_11, if x_11 sleeps, then x_11 is excited can be inferred via the universal biconditional elimination rule. For all x_11, if x_11 were excited, then x_11 is sleeping can be inferred via the universal biconditional elimination rule.