  This is a technical report, containing all the lemma and proposition proofs
in paper "Topological Constraints on Identifying Additive Link Metrics via
End-to-end Paths Measurements" by Liang Ma, Ting He, Kin K. Leung, Don Towsley,
and Ananthram Swami, published in Annual Conference of The International
Technology Alliance (ACITA), 2012.
