The edge-removal problem asks whether the removal of a $lambda$-capacity edge from a given network can decrease the communication rate between source-terminal pairs by more than $lambda$. In this short manuscript, we prove that for undirected networks, removing a $lambda$-capacity edge decreases the rate by $O(lambda)$. Through previously known reductive arguments, here newly applied to undirected networks, our result implies that the zero-error capacity region of an undirected network equals its vanishing-error capacity region. Whether it is possible to prove similar results for directed networks remains an open question.
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