What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_6, x_6 will not play tennis. For all x_6, x_6 is a doctor if and only if x_6 will play squash. For all x_6, x_6 will play tennis or x_6 will write a letter. For all x_6, if x_6 plays squash, then x_6 is not writing a letter.
For all x_6, x_6 will write a letter. For all x_6, if x_6 were a doctor, then x_6 is playing squash. For all x_6, if x_6 plays squash, then x_6 is a doctor.