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: It is late if and only if David is sleeping. If it is cloudy, then it is late. If it is sunny, then David is sleeping. It is sunny or it is cloudy.
If it is late, then David is sleeping can be inferred via the biconditional elimination rule. If David sleeps, then it is late can be inferred via the biconditional elimination rule.