2 problems

Let $\textup{ex}(n,\{C_3,C_4\})$ be the maximum number of edges in an $n$-vertex graph containing no cycle of length three or four. Let $z(n,C_4)$ be the maximum number of edges in…

Let $\textup{ex}(n,\{C_3,C_4\})$ denote the maximum number of edges in an $n$-vertex graph containing no cycle of length three or four. The incidence graph of a projective plane gi…