Identification via the broadcast channel

We show that the identification (ID) capacity of the two-receivers broadcast channel is the set of rate pairs satisfying that, for some distribution on the input, each receiver´s ID rate does not exceed the mutual information between the input and the output that it observes. The capacity´s interior is achieved by codes with deterministic encoders. Our results hold under the average error criterion, which requires that each receiver reliably identify its message if the other receiver´s message is uniformly distributed. Key in the proof is a new ID code for the single-user channel.