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