I was really confused at his example here, so I drew this: http://i.imgur.com/NBVPiCE.png http://i.imgur.com/NBVPiCE.png then I realized that his example was

I was really confused at his example here, so I drew this: http://i.imgur.com/NBVPiCE.png http://i.imgur.com/NBVPiCE.png then I realized that his example was meant to be interpreted as a single disconnected graph, rather than two separate examples.