What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: For all x_4, if x_4 plays squash, then x_4 is an office clerk. For all x_4, x_4 is an office clerk if and only if x_4 will play squash. Michael is an office clerk.
There is at least one x for which x is an office clerk can be inferred via the existential generalization rule. For all x_4, if x_4 were an office clerk, then x_4 is playing squash can be inferred via the universal biconditional elimination rule. For all x_4, if x_4 plays squash, then x_4 is an office clerk can be inferred via the universal biconditional elimination rule.