Star arboricity

Astar forest is a forest all of whose components are stars. Thestar arboricity, st(G) of a graphG is the minimum number of star forests whose union covers all the edges ofG. Thearboricity, A(G), of a graphG is the minimum number of forests whose union covers all the edges ofG. Clearlyst(G)≥A(G). In fact, Algor and Alon have given examples which show that in some casesst(G) can be as large asA(G)+Ω(logΔ) (where Δ is the maximum degree of a vertex inG). We show that for any graphG, st(G)≤A(G)+O(logΔ).