The Zarankiewics Problem for $K_{2,2}$. Upper bound.

Question

This problem has proved to give me a lot of trouble. Please provide a complete solution for me.

Find the Upper Bound for $ex(n, K_{2,2}) = \Omega(n^\frac{3}{2})$ edges.

We say $f(n) = \sigma(g(n))$ if $f(n) = O(g(n))$ and $f(n) = \Omega(g(n))$

I am sorry I cannot provide more details. I am new to grasping this subject.

Answer 1

Here is a good source that I found: Zarankiewics Link!

There is a proof for ex(n, K_2,2 ) = $O(n^\frac{3}{2})$