What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? There is at least one z for which if z were a scientist, then z is a mechanic. For all z, if z were a writer, then z is a scientist. For all z, if z writes a letter, then z is a writer. For all z, if z were a mechanic, then z is a cashier.
For all z, if z writes a letter, then z is a scientist. There is at least one z for which if z were a scientist, then z is a cashier. There is at least one z for which if z were a writer, then z is a mechanic.