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The abstract model of the multi-hop relay channel is fundamental to a vast variety of modern communication systems. This fact, coupled with the demand for ultra-reliable-low-latency communication (URLLC), motivates a new investigation of relay channels from a delay-vs-throughput perspective. This work seeks to analyze this tradeoff in the regime of asymptotically large, yet still finite delay. A new metric called the Delay Amplification Factor (DAF) is introduced, which allows analytic comparison of the asymptotic delay across different relay solutions, e.g. decode-&-forward (DF), compress-&-forward, etc. The optimal DAF (over all possible existing/future designs) is then characterized for two special settings, one with fixed-length coding and one with variable-length coding and 1-bit stop feedback. The results show that under some general conditions, the optimal end-to-end delay over an L-hop line network is …