What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_13, x_13 will play squash if and only if x_13 is a mechanic. There is at least one x_13 for which if x_13 were a mechanic, then x_13 is playing squash. For all x_13, if x_13 plays squash, then x_13 is a mechanic.
There is at least one x_13 for which x_13 is a mechanic if and only if x_13 will play squash. There is at least one x_13 for which x_13 will play squash if and only if x_13 is a mechanic. For all x_13, if x_13 plays squash, then x_13 is a mechanic. For all x_13, if x_13 were a mechanic, then x_13 is playing squash.