What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? James is not playing tennis. If Richard plays squash, then James is playing tennis. If Jessica were an astronaut, then Richard is writing a letter. Richard is writing a letter if and only if Jessica is an astronaut. Richard is writing a letter if and only if Richard is playing squash.
Richard is not playing squash. If Richard writes a letter, then Jessica is an astronaut. If Richard writes a letter, then Richard is playing squash. If Jessica were an astronaut, then Richard is writing a letter. If Richard plays squash, then Richard is writing a letter.