I have a question about the paper "Feasibility of Interference Alignment for the MIMO Interference Channel" by Bresler, Cartwright and Tse, IEEE Tran Information Theory, Vol. 60, Issue 9, page 5574.
In proving Theorem 1, they invoked Theorem 9. But it seems to me that conclusion (2) of Theorem 9 was used but the conditions for such conclusion was not justified in the proof.
Does anyone understand that part? I wish to discuss further about that proof.