  We consider the 3-user Gaussian interference channel and provide an outer
bound on its capacity region. Under some conditions, which we call the mixed
strong-very strong interference conditions, this outer bound is achievable.
These conditions correspond to the case where at each receiver, one transmitter
is causing strong interference and the other is causing very strong
interference. Therefore, we characterize the capacity region of the 3-user
interference channel with mixed strong-very strong interference.
