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 Elisabeth were a carpenter, then Sarah is writing a letter. Elisabeth is a carpenter and Barbara is reading a book. If Sarah writes a letter, then John is taking a plane.
If Elisabeth were a carpenter, then John is taking a plane can be inferred via the transitivity rule. Elisabeth is a carpenter can be inferred via the simplification rule. Barbara is reading a book can be inferred via the simplification rule.