What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Thomas is working if and only if it is late. Thomas is not working. Sarah is not running or Susan is happy. Sarah is running.
Thomas is not working and Sarah is running. Sarah is running and Thomas is not working. If Thomas works, then it is late. If it is late, then Thomas is working. It is not late.