What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_4, if x_4 plays squash, then x_4 is a musician. For all x_4, if x_4 were a musician, then x_4 is playing squash. For all x_4, if x_4 plays squash, then x_4 is a musician.
For all x_4, x_4 will play squash if and only if x_4 is a musician. For all x_4, x_4 is a musician if and only if x_4 will play squash. For all x_4, x_4 is a musician if and only if x_4 will play squash. For all x_4, x_4 will play squash if and only if x_4 is a musician.