（子）图同构算法VF2实现（1）

子图同构问题本质上就是一种匹配，VF2算法加了很多feasibility rules，保证了算法的高效性。这里只是实现最基本的判断子图同构的算法：

参考文献有（其实google一把就能出来这些）：

http://stackoverflow.com/questions/8176298/vf2-algorithm-steps-with-example

http://www.zhihu.com/question/27071897

https://github.com/fozziethebeat/S-Space/tree/master/src/main/java/edu/ucla/sspace/graph/isomorphism

http://stackoverflow.com/questions/6743894/any-working-example-of-vf2-algorithm/6744603

Luigi P. Cordella,Pasquale Foggia,Carlo Sansone,Mario Vento: A (Sub)Graph Isomorphism Algorithm for Matching Large Graphs.IEEE Trans. Pattern Anal. Mach. Intell. 26(10): 1367-1372 (2004)

第一个链接给了一个示例：

http://stackoverflow.com/questions/8176298/vf2-algorithm-steps-with-example：

I will try to give you a quick explaination of my previous answer to this question :

Any working example of VF2 algorithm?

I will use the same example as the one in my previous answer :

enter image description here

The 2 graphs above are V and V' .(V' is not in the drawing but it's the one on the right)

The VF2 algorithm is described in the graph.