What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Sarah is an astronaut if and only if it is late. It is not late. Linda is sad.
It is not late and Linda is sad. Linda is sad and it is not late. If Sarah were an astronaut, then it is late. If it is late, then Sarah is an astronaut. Sarah is not an astronaut.