0 Beginning

1 The Origin of Graph Theory

1.1 The Origin of Graph Theory

Introduction of the origin of graph theory, including how the idea of developing graph theory is intrigued, the people who were involved, and the problems that were correlated with the theorem.

1.2 Seven Bridges of Königsberg Problem

1.3 Euler’s Proof of the Problem

2 Hamilton’s “A Voyage Round the World” Puzzle

3 Four Color Theorem

4 Tree

4.1 The history of Tree

4.2 Cayley's formula

4.3 Proof of Cayley’s Formula