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: If Karen cooks, then David is working. For all x_10, if x_10 works, then x_10 is a writer. For all x_10, if x_10 were a writer, then x_10 is working.
For all x_10, x_10 will work if and only if x_10 is a writer can be inferred via the universal biconditional introduction rule. For all x_10, x_10 is a writer if and only if x_10 will work can be inferred via the universal biconditional introduction rule.