The definition of PPAD (Polynomial parity arguments on directed graphs) revolves around the definition of "End-Of-The-Line"
An exponentially large polynomial-depth arithmetic circuit, $f$, specifies a graph where every node has an in-degree and out-degree of at most $1$. Given that $0$'s in-degree doesn't match it's out-degree, find another node where the in-degree isn't equal to its out-degree
I don't understand why we can't just sub in arithmetic circuits with boolean circuits here.
