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Approximate Counting of $k$-Paths in $O^*(2^k)$ Time

Aug 2026 · 0 citations · 21 references
Computer Science

TL;DR

A randomized algorithm returns a $(1\pm\varepsilon)-approximation with failure probability at most $\delta$ in $O^*(2^k\varepsilon^{-2}\log(1/\delta)$ time.

Abstract

We resolve the conjecture of Koutis and Williams that $k$-paths can be approximately counted in $O^*(2^k)$ time. For a simple directed graph with $n$ vertices and $m$ arcs, our randomized algorithm returns a $(1\pm\varepsilon)$-approximation with failure probability at most $\delta$ in $O^*(2^k\varepsilon^{-2}\log(1/\delta))$ time.

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