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: William is a bartender if and only if Barbara is poor. If Barbara were poor, then Jessica is an artist. If it snows, then William is a bartender. Jessica is not an artist. William is a bartender if and only if it is snowing.
Barbara is not poor can be inferred via the modus tollens rule. If William were a bartender, then Barbara is poor can be inferred via the biconditional elimination rule. If William were a bartender, then it is snowing can be inferred via the biconditional elimination rule. If Barbara were poor, then William is a bartender can be inferred via the biconditional elimination rule. If it snows, then William is a bartender can be inferred via the biconditional elimination rule.