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: Susan is a bartender if and only if Joseph is taking a plane. It is cloudy. Susan is a bartender.
It is cloudy and Susan is a bartender can be inferred via the conjunction rule. Susan is a bartender and it is cloudy can be inferred via the conjunction rule. If Susan were a bartender, then Joseph is taking a plane can be inferred via the biconditional elimination rule. If Joseph takes a plane, then Susan is a bartender can be inferred via the biconditional elimination rule.