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 is not a carpenter. There is at least one x_18 for which x_18 will work if and only if x_18 is a carpenter. For all x_18, x_18 will work or x_18 will take a plane. For all x_18, x_18 is an astronaut.
There is at least one x_18 for which if x_18 works, then x_18 is a carpenter. There is at least one x_18 for which if x_18 were a carpenter, then x_18 is working. There is at least one x_18 for which x_18 will not work.