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: For all x, x is a writer if and only if x is a politician. Elisabeth is a politician or Karen is not listening to a song. Karen is listening to a song.
If Karen listens to a song, then Elisabeth is a politician can be inferred via the rewriting rule. For all x, if x were a writer, then x is a politician can be inferred via the universal biconditional elimination rule. For all x, if x were a politician, then x is a writer can be inferred via the universal biconditional elimination rule.