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 sunny or Susan is not cooking. If Susan cooks, then it is sunny. If it is sunny, then Susan is cooking.
If Susan cooks, then it is sunny can be inferred via the rewriting rule. Susan is cooking if and only if it is sunny can be inferred via the biconditional introduction rule. It is sunny if and only if Susan is cooking can be inferred via the biconditional introduction rule.