Catalog

One , Undirected and directed graphs

Two , The representation of the figure

3、 ... and , Common concepts of graph

1, Parallel sides （ Multiple sides ）

2, Simple picture

3, Connected component

Four , The kernel of a digraph

One , Undirected and directed graphs

The graph consists of nodes and edges .

According to whether the edge has direction , The picture is divided into Undirected graph and Directed graph .

Two , The representation of the figure

There are three common representations ： Adjacency list 、 Adjacency matrix 、 Side set .

The three representations are used to express undirected graphs and directed graphs in the same way .

3、 ... and , Common concepts of graph

1, Parallel sides （ Multiple sides ）

In the undirected graph , If there are more undirected edges associated with a pair of vertices than 1 strip , These edges are called parallel edges .
In a directed graph , If there are more directed edges associated with a pair of vertices than 1 strip , And the start point of these edges is the same as the end point ( That is, they have the same direction ), Call these edges parallel .

2, Simple picture

A graph with parallel edges is called a multigraph , A graph that contains neither parallel edges nor self rings is called a simple graph .

3, Connected component

Generally, only undirected graphs can talk about this concept , Connected components refer to the fact that a graph is divided into several unconnected parts .

Be careful , A graph with only one point and no edges is also a graph .

Four , The kernel of a digraph

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