What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? It is not late. If Mary plays tennis, then it is late. Thomas is reading a book if and only if Mary is playing tennis. If it is late, then Mary is playing tennis.
Mary is not playing tennis. Mary is playing tennis if and only if it is late. It is late if and only if Mary is playing tennis. If Thomas reads a book, then Mary is playing tennis. If Mary plays tennis, then Thomas is reading a book.