What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Sarah is taking a plane if and only if Jennifer is an electrician. Sarah is not playing squash. For all z_3, z_3 will take a plane if and only if z_3 will play squash.
If Sarah takes a plane, then Jennifer is an electrician. If Jennifer were an electrician, then Sarah is taking a plane. For all z_3, if z_3 takes a plane, then z_3 is playing squash. For all z_3, if z_3 plays squash, then z_3 is taking a plane.