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: Elisabeth is not climbing a mountain. It is sunny or David is not cooking. If it is sunny, then David is cooking. Elisabeth is climbing a mountain if and only if it is sunny.
If David cooks, then it is sunny can be inferred via the rewriting rule. If Elisabeth climbs a mountain, then it is sunny can be inferred via the biconditional elimination rule. If it is sunny, then Elisabeth is climbing a mountain can be inferred via the biconditional elimination rule. It is not sunny can be inferred via the biconditional elimination rule.