Graph Isomorphism was not thought to be NP-hard. In fact, it's been a struggle to come up with any hard instances of the problem. If Babai's work turns out to b

Graph Isomorphism was not thought to be NP-hard. In fact, it's been a struggle to come up with any hard instances of the problem. If Babai's work turns out to be correct, it just confirms that there aren't really any hard instances.