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_8, x_8 will read a book if and only if x_8 is sad. There is at least one x_8 for which x_8 is sad or x_8 is a soldier. For all x_8, x_8 will not read a book.
For all x_8, if x_8 reads a book, then x_8 is sad can be inferred via the universal biconditional elimination rule. For all x_8, if x_8 were sad, then x_8 is reading a book can be inferred via the universal biconditional elimination rule. For all x_8, x_8 is not sad can be inferred via the universal biconditional elimination rule.