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: William is cooking if and only if Elisabeth is rich. William is not cooking. For all x_7, x_7 is rich if and only if x_7 will read a book.
If William cooks, then Elisabeth is rich can be inferred via the biconditional elimination rule. If Elisabeth were rich, then William is cooking can be inferred via the biconditional elimination rule. Elisabeth is not rich can be inferred via the biconditional elimination rule. For all x_7, if x_7 were rich, then x_7 is reading a book can be inferred via the universal biconditional elimination rule. For all x_7, if x_7 reads a book, then x_7 is rich can be inferred via the universal biconditional elimination rule.