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 David were a taxi driver, then Jessica is working. If Charles were an artist, then David is a taxi driver. Charles is an artist if and only if Jessica is working.
If Charles were an artist, then Jessica is working can be inferred via the transitivity rule. If Charles were an artist, then Jessica is working can be inferred via the biconditional elimination rule. If Jessica works, then Charles is an artist can be inferred via the biconditional elimination rule.