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: Joseph is not drinking water or Elisabeth is a scientist. If it is cloudy, then James is taking a plane. John is an astronaut if and only if James is taking a plane. John is not an astronaut. Joseph is drinking water or it is cloudy.
It is cloudy or Elisabeth is a scientist can be inferred via the resolution rule. If John were an astronaut, then James is taking a plane can be inferred via the biconditional elimination rule. If James takes a plane, then John is an astronaut can be inferred via the biconditional elimination rule. James is not taking a plane can be inferred via the biconditional elimination rule.