Simple and local independent set approximation

We study the worst-case behavior of Turán-like bounds for unweighted and weighted independent sets in bounded-degree graphs. In particular, we revisit a randomized approach of Boppana that forms a simple 1-round distributed algorithm, as well as a streaming algorithm and a preemptive online algorithm. We show that it gives a tight (Δ+1)/2-approximation in unweighted graphs of maximum degree Δ, which is best possible for 1-round distributed algorithms. For weighted graphs, it gives only a (Δ+1)-approximation, but a simple modification results in an asymptotic expected 0.529(Δ+1)-approximation.