Turán problems and shadows II: Trees

Here we continue this project by determining the asymptotics for ex3(n,G+) when G is any fixed forest. This settles a conjecture of Füredi [7]. Using our methods, we also show that for any graph G, either ex3(n,G+)≤(12+o(1))n2 or ex3(n,G+)≥(1+o(1))n2, thereby exhibiting a jump for the Turán number of expansions.