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_8, x_8 is poor if and only if x_8 will play squash. There is at least one x_8 for which x_8 will play squash or x_8 will not take a plane. For all x_8, x_8 is not poor.
There is at least one x_8 for which if x_8 takes a plane, then x_8 is playing squash can be inferred via the existential rewriting rule. For all x_8, if x_8 were poor, then x_8 is playing squash can be inferred via the universal biconditional elimination rule. For all x_8, if x_8 plays squash, then x_8 is poor can be inferred via the universal biconditional elimination rule. For all x_8, x_8 will not play squash can be inferred via the universal biconditional elimination rule.