Simple Graph of Maximum Size is Complete Graph/Examples/Order 4

Examples of Use of Simple Graph of Maximum Size is Complete Graph
Let $G$ be the simple graph of order $4$ whose edge set $E$ is as large as possible.

Then the size of $G$ is given by:
 * $\size E = 6$

Proof
By Simple Graph of Maximum Size is Complete Graph:
 * $G = K_4$

From Size of Complete Graph:
 * $\size E = \dfrac {4 \times \paren {4 - 1} } 2 = \dfrac {12} 2 = 6$