What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Jennifer is fast if and only if Richard is a doctor. For all x_19, x_19 will not write a letter. William is writing a letter if and only if Jennifer is fast.
If Jennifer were fast, then Richard is a doctor. If William writes a letter, then Jennifer is fast. If Richard were a doctor, then Jennifer is fast. If Jennifer were fast, then William is writing a letter.