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: David is a politician if and only if Robert is reading a book. David is a politician or it is not cloudy. If Robert reads a book, then it is cloudy.
If it is cloudy, then David is a politician can be inferred via the rewriting rule. If David were a politician, then Robert is reading a book can be inferred via the biconditional elimination rule. If Robert reads a book, then David is a politician can be inferred via the biconditional elimination rule.