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 y, y is a server if and only if y will play tennis. There is at least one y for which if y were a server, then y is curious. For all y, if y were curious, then y is playing tennis.
There is at least one y for which if y were a server, then y is playing tennis can be inferred via the existential transitivity rule. For all y, if y were a server, then y is playing tennis can be inferred via the universal biconditional elimination rule. For all y, if y plays tennis, then y is a server can be inferred via the universal biconditional elimination rule.