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 it is late, then Patricia is taking a plane. Linda is not sad. If Patricia takes a plane, then Linda is sad. If Linda were sad, then it is late.
Patricia is not taking a plane can be inferred via the modus tollens rule. If it is late, then Linda is sad can be inferred via the transitivity rule. If Patricia takes a plane, then it is late can be inferred via the transitivity rule. If Linda were sad, then Patricia is taking a plane can be inferred via the transitivity rule.