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: For all x_10, if x_10 were a writer, then x_10 is sad. If Sarah were happy, then Joseph is a writer. If Joseph were sad, then Sarah is happy.
If Joseph were sad, then Joseph is a writer can be inferred via the transitivity rule.