An independent broadcast on a connected graph G is function f:V(G)→N0 such that, for every vertex x of G, the value f(x) at most eccentricity in and f(x)>0 implies that f(y)=0 y within distance from x. The independence number αb(G) largest weight ∑x∈V(G)f(x) an f G. We describe efficient algorithm determines given tree. Furthermore, we show NP-hardness planar graphs maximum degree four, hardnes...