What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_18, x_18 will cook if and only if x_18 is a doctor. There is at least one x_18 for which x_18 will cook or x_18 will not write a letter. For all x_18, x_18 is a doctor or x_18 will write a letter.
There is at least one x_18 for which if x_18 writes a letter, then x_18 is cooking. For all x_18, if x_18 cooks, then x_18 is a doctor. For all x_18, if x_18 were a doctor, then x_18 is cooking.