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 take a plane if and only if z will cook. For all z, if z takes a plane, then z is working. For all z, if z works, then z is taking a plane. For all z, z will not cook.
For all z, z will take a plane if and only if z will work can be inferred via the universal biconditional introduction rule. For all z, z will work if and only if z will take a plane can be inferred via the universal biconditional introduction rule. For all z, if z takes a plane, then z is cooking can be inferred via the universal biconditional elimination rule. For all z, if z cooks, then z is taking a plane can be inferred via the universal biconditional elimination rule. For all z, z will not take a plane can be inferred via the universal biconditional elimination rule.