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_7, if x_7 goes running, then x_7 is an office clerk. There is at least one x_7 for which if x_7 were an office clerk, then x_7 is reading a book. For all x_7, if x_7 reads a book, then x_7 is an office clerk.
There is at least one x_7 for which if x_7 goes running, then x_7 is reading a book can be inferred via the existential transitivity rule. There is at least one x_7 for which x_7 is an office clerk if and only if x_7 will read a book can be inferred via the existential biconditional introduction rule. There is at least one x_7 for which x_7 will read a book if and only if x_7 is an office clerk can be inferred via the existential biconditional introduction rule.