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 Richard were a scientist, then Sarah is reading a book. For all y_1, y_1 will go running. If Joseph goes running, then Richard is a scientist. James is a taxi driver if and only if Richard is a scientist.
If Joseph goes running, then Sarah is reading a book can be inferred via the transitivity rule. If James were a taxi driver, then Richard is a scientist can be inferred via the biconditional elimination rule. If Richard were a scientist, then James is a taxi driver can be inferred via the biconditional elimination rule.