What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Mary is writing a letter or it is not raining. For all x_4, if x_4 writes a letter, then x_4 is excited. For all x_4, if x_4 were excited, then x_4 is writing a letter.
If it rains, then Mary is writing a letter. For all x_4, x_4 will write a letter if and only if x_4 is excited. For all x_4, x_4 is excited if and only if x_4 will write a letter.