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_9, x_9 will not work. There is at least one x_9 for which if x_9 were poor, then x_9 is a sailor. For all x_9, x_9 is a sailor if and only if x_9 will work. For all x_9, if x_9 plays squash, then x_9 is poor.
There is at least one x_9 for which if x_9 plays squash, then x_9 is a sailor can be inferred via the existential transitivity rule. For all x_9, if x_9 were a sailor, then x_9 is working can be inferred via the universal biconditional elimination rule. For all x_9, if x_9 works, then x_9 is a sailor can be inferred via the universal biconditional elimination rule. For all x_9, x_9 is not a sailor can be inferred via the universal biconditional elimination rule.