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: Jessica is a scientist. If John takes a plane, then it is not late. It is late.
John is not taking a plane can be inferred via the modus tollens rule. Jessica is a scientist and it is late can be inferred via the conjunction rule. It is late and Jessica is a scientist can be inferred via the conjunction rule.