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_11, x_11 will sleep if and only if x_11 is an office clerk. It is late. Barbara is not an office clerk.
It is late and Barbara is not an office clerk can be inferred via the conjunction rule. Barbara is not an office clerk and it is late can be inferred via the conjunction rule. For all x_11, if x_11 sleeps, then x_11 is an office clerk can be inferred via the universal biconditional elimination rule. For all x_11, if x_11 were an office clerk, then x_11 is sleeping can be inferred via the universal biconditional elimination rule.