this special class, each diamond channel consists of a transmitter, a noisy relay, a noiseless
relay and a receiver. We prove the capacity of this class of diamond channels by providing
an achievable scheme and a converse. The capacity we show is strictly smaller than the cut-
set bound. Our result also shows the optimality of a combination of decode-and-forward
(DAF) and compress-and-forward (CAF) at the noisy relay node. This is the first example …