Basics of Graph Theory

Graphs are used in mathematics to describe a variety of problems and situations [.37. The methods of graph theoi y analyze graphs and the problems modeled by them, The transfer of models and abstractions from other sciences (computer science, chemistry, physics, economics, sociology, etc.) to graph theory makes it possible to process them mathematically because of the easily understandable basics of graph theory. 

Some fundamental definitions of graph theoi y are given in Table 2-4. 

Nodes (dots) ai e adjacent when they are connected by the same edge. 

If the nodes of a graph are marked (e.g., witli digits), the graph is termed labeled. In the example, node I is adfacent to node 2 bnt not to node 3. 

The degree (or valency) of a node is deiennined by the number of distinct edges that end in a given node, (e.g., nodes 1 and 3 liave the degree 1, and node 2 has the degree 2), 

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