From 2007.igem.org

The Missouri Western team has proposed to build this graph, which has an edge from node 1 to 2, 2 to 3, and 1 to 3. In order to determine the likelihood that the biology should find the Hamiltonian path within this directed graph, Western has looked at starting arrangements which should be identified as easy, medium, and hard.

For the time being, an easy starting arrangement should be identified as one which, with one flip, can find a true postive. Similarily, a medium starting arrangement can find a true positive within 2 flips and and a hard can find a true positive within 3 flips.