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_6, if x_6 reads a book, then x_6 is playing tennis. There is at least one x_6 for which x_6 will play tennis if and only if x_6 will read a book.
There is at least one x_6 for which if x_6 plays tennis, then x_6 is reading a book can be inferred via the existential biconditional elimination rule. There is at least one x_6 for which if x_6 reads a book, then x_6 is playing tennis can be inferred via the existential biconditional elimination rule.