\begin{lem} If two packets $t$ and $u$, with $i(t) \le i(u)$, are received without errors by a client $C$, then $t$ is in the path of $u$. \end{lem}\r
\begin{proof}\r
Assume that $t$ is not in the path of $u$. Take $u$ to be the packet of smallest index for which this occurs, and $t$ be the packet with largest index for this $u$. We will prove that an error occurs upon receipt of $u$.\r
\begin{lem} If two packets $t$ and $u$, with $i(t) \le i(u)$, are received without errors by a client $C$, then $t$ is in the path of $u$. \end{lem}\r
\begin{proof}\r
Assume that $t$ is not in the path of $u$. Take $u$ to be the packet of smallest index for which this occurs, and $t$ be the packet with largest index for this $u$. We will prove that an error occurs upon receipt of $u$.\r