Graph Terminology I

Learn about the fundamental concepts of graph theory, such as adjacency and paths.

Adjacency

For an edge e=(u,v)e = (u, v) that connects node uu to node vv, we say that vv is adjacent to uu, or that vv is a neighbor of uu. The edge ee is called incident to both uu and vv.

The number of neighbors of a node vv is called the degree of vv, written deg(vv).

In the following example graph, cc is a neighbor of bb, as there is an edge (b,c)(b, c). But bb is not a neighbor of cc, as there is no edge (c,b)(c, b). The degree of node aa is deg(a)=2(a) = 2, as it has two neighbors.

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