What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Thomas is not a lawyer. For all x, x will read a book. Mary is sad if and only if Joseph is driving a car. Mary is sad if and only if Thomas is a lawyer.
If Mary were sad, then Joseph is driving a car. If Mary were sad, then Thomas is a lawyer. If Joseph drives a car, then Mary is sad. If Thomas were a lawyer, then Mary is sad. Mary is not sad.