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: If Barbara were a server, then it is cloudy. Barbara is a server if and only if Linda is working. Barbara is a server or it is not cloudy.
If it is cloudy, then Barbara is a server can be inferred via the rewriting rule. If Barbara were a server, then Linda is working can be inferred via the biconditional elimination rule. If Linda works, then Barbara is a server can be inferred via the biconditional elimination rule.