graph problem

[spyroy]

how many circles in size 4 there are in a Ka,b graph?
(Ka,b is a complete double sided graph with a vertices in one side and b in the other)
i tried to say that we choose 2 from - a, so - a choose 2, and 2 from - b so - a choose 2 * b choose 2
but that doesnt work...

 

[Dr.Peterson]

I think you are asking about the number of cycles in a complete bipartite graph.

If so, I think your answer sounds reasonable. In what sense does it "not work"?

 

[spyroy]

I think you are asking about the number of cycles in a complete bipartite graph.

If so, I think your answer sounds reasonable. In what sense does it "not work"?

yes i did meant that but when i chcked that on K3,3 i thoght it has 6 circles but now i see its 9
so i guess it works, thank you.