Sorry for a silly question, I got confused with the definition of bipartite graph.
What is a necessary and sufficient condition for a bipartite graph.
A bipartite graph has not odd circle
The above property defined as a sufficient conditions, does it mean that all possible even circles is absolutely eligible in bipartite graph?
It's of course a necessary condition, but I am not sure whether it is a sufficient.
Addendum:
What's wrong in the following graph with even circle?