What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If it is late, then John is an astronaut. Susan is a taxi driver. John is not an astronaut. It is late if and only if Thomas is playing squash.
It is not late. Susan is a taxi driver and John is not an astronaut. John is not an astronaut and Susan is a taxi driver. If it is late, then Thomas is playing squash. If Thomas plays squash, then it is late.