What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_11, x_11 will work or x_11 will not write a letter. There is at least one x_11 for which if x_11 works, then x_11 is writing a letter. For all x_11, if x_11 writes a letter, then x_11 is working.
For all x_11, if x_11 writes a letter, then x_11 is working. There is at least one x_11 for which x_11 will work if and only if x_11 will write a letter. There is at least one x_11 for which x_11 will write a letter if and only if x_11 will work.