1.图的知识总览
![](https://img.haomeiwen.com/i19531096/277afacbf4eb978b.png)
2.图的定义
图G由顶点集V和边集E组成,记为G=(V,E),其中V(G)表示图G中顶点的有限非空集;E(G)表示图G中顶点之间的关系(边)的集合
|V| 表示图G中顶点的个数,也称图G的阶;|E| 表示图G中的边的条数
![](https://img.haomeiwen.com/i19531096/5fc145cd58f9ecaa.png)
3.有向图和无向图
![](https://img.haomeiwen.com/i19531096/3d25284dbf1e0d2b.png)
4.简单图和多重图
![](https://img.haomeiwen.com/i19531096/ddbca080a751d760.png)
5.完全图
![](https://img.haomeiwen.com/i19531096/1de1062194368671.png)
6.子图
![](https://img.haomeiwen.com/i19531096/45538fe82fb41878.png)
![](https://img.haomeiwen.com/i19531096/b5d907dd6217a26e.png)
![](https://img.haomeiwen.com/i19531096/ad3ff97b44245b61.png)
由于子图的定义只是说明子集,没有说明真子集,所以相等的图也是子图
![](https://img.haomeiwen.com/i19531096/663b028d59b6fef5.png)
由于图的边集可以为空,所以无边子图也是符合定义的子图
![](https://img.haomeiwen.com/i19531096/937081cd6338e746.png)
根据图的定义,边是代表顶点之间的关系,所以边必须有两个端点,上面的图片中有一条边只有一个端点,完全不符合图的定义所以不是图,所以更不能称之为子图
7.连通图和强连通图
连通和强连通定义如下
![](https://img.haomeiwen.com/i19531096/b533fec0e7dab3e4.png)
连通图和强连通图的定义如下
![](https://img.haomeiwen.com/i19531096/3868a907ec07b9ba.png)
N个顶点的连通图和强连通图最少有多少条边?
![](https://img.haomeiwen.com/i19531096/a29bd5c94db4f42f.png)
连通分量(极大连通子图)与强连通分量(极大强连通子图)
![](https://img.haomeiwen.com/i19531096/d553cf9b73cba1e3.png)
无向图连通分量(极大连通子图)
![](https://img.haomeiwen.com/i19531096/9eb20014ec42fc52.png)
有向图强连通分量(极大强连通子图)
![](https://img.haomeiwen.com/i19531096/2bb75d301351d803.png)
如果原图是一个连通图或强连通图,那该图的连通分量或强连通分量都是与原图一样的,如果原图并不是一个连通图或强连通图,那该图的连通分量或强连通分量会是有多个的
8.生成树、生成森林
![](https://img.haomeiwen.com/i19531096/b6c2299eb0ea68dd.png)
![](https://img.haomeiwen.com/i19531096/4514d23842d71db1.png)
![](https://img.haomeiwen.com/i19531096/a09e59e996360104.png)
9.顶点的度
![](https://img.haomeiwen.com/i19531096/6cdca2312f27d7c6.png)
10.网
![](https://img.haomeiwen.com/i19531096/3a1a4466138595ee.png)
11.稠密图与稀疏图
![](https://img.haomeiwen.com/i19531096/3c76dc5dceecb88a.png)
12.有向树
![](https://img.haomeiwen.com/i19531096/efd11434c424ab8e.png)
13.路径
![](https://img.haomeiwen.com/i19531096/d9eea06a7053bd92.png)
![](https://img.haomeiwen.com/i19531096/3b9e4eb094c3d4fe.png)
![](https://img.haomeiwen.com/i19531096/2708cdffba96ba8c.png)
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