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 z, z will play a game if and only if z will read a book. There is at least one z for which z will play a game if and only if z will read a book.
For all z, if z plays a game, then z is reading a book can be inferred via the universal biconditional elimination rule. There is at least one z for which if z plays a game, then z is reading a book can be inferred via the existential biconditional elimination rule. For all z, if z reads a book, then z is playing a game can be inferred via the universal biconditional elimination rule. There is at least one z for which if z reads a book, then z is playing a game can be inferred via the existential biconditional elimination rule.