What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Barbara is writing a letter or Barbara is not an electrician. For all x_12, x_12 will write a letter if and only if x_12 is an electrician.
If Barbara were an electrician, then Barbara is writing a letter. For all x_12, if x_12 writes a letter, then x_12 is an electrician. For all x_12, if x_12 were an electrician, then x_12 is writing a letter.