  We provide a single-letter characterization for the capacity region of a
class of discrete degraded interference channels (DDICs). The class of DDICs
considered includes the discrete additive degraded interference channel (DADIC)
studied by Benzel. We show that for the class of DDICs studied, encoder
cooperation does not increase the capacity region, and therefore, the capacity
region of the class of DDICs is the same as the capacity region of the
corresponding degraded broadcast channel.
