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: There is at least one x_13 for which x_13 is happy. For all x_13, x_13 will sleep if and only if x_13 is happy. For all x_13, x_13 will read a book.
There is at least one x_13 for which x_13 is happy and x_13 will read a book can be inferred via the existential conjunction rule. There is at least one x_13 for which x_13 will read a book and x_13 is happy can be inferred via the existential conjunction rule. For all x_13, if x_13 sleeps, then x_13 is happy can be inferred via the universal biconditional elimination rule. For all x_13, if x_13 were happy, then x_13 is sleeping can be inferred via the universal biconditional elimination rule.