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: William is a carpenter or it is late. If Elisabeth plays squash, then it is raining. Elisabeth is playing squash if and only if William is a carpenter. If it is late, then it is raining.
If Elisabeth plays squash, then William is a carpenter can be inferred via the biconditional elimination rule. If William were a carpenter, then Elisabeth is playing squash can be inferred via the biconditional elimination rule.