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 for which x will not drink water. For all x, x will sleep if and only if x will drink water. For all x, x will sleep or x will not drink water.
For all x, if x drinks water, then x is sleeping can be inferred via the universal rewriting rule. For all x, if x sleeps, then x is drinking water can be inferred via the universal biconditional elimination rule. For all x, if x drinks water, then x is sleeping can be inferred via the universal biconditional elimination rule. There is at least one x for which x will not sleep can be inferred via the existential biconditional elimination rule.