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 it is overcast, then Charles is listening to a song. If Charles were a lawyer, then it is overcast. Charles is a lawyer if and only if Charles is listening to a song.
If Charles were a lawyer, then Charles is listening to a song can be inferred via the transitivity rule. If Charles were a lawyer, then Charles is listening to a song can be inferred via the biconditional elimination rule. If Charles listens to a song, then Charles is a lawyer can be inferred via the biconditional elimination rule.