Is there a textbook/paper that I can reference for the following problem? I am looking for a concise proof that I can cite.
Let $G=(V,E)$ be a weighted directed acyclic graph, and consider $s,t\in V$. Calculate the sum of products of weights along all $s-t$ paths.
The solution is a relatively straightforward dynamic programming algorithm, so I believe there must be some text where the proof is discussed. I tried inspecting the DP chapters of standard algorithms texts (CLRS, Dasgupta), but I can't see anything similar.