 Solution

ID: past-exam-of-the-probability-statistics-and-options-ii-course-of-the-university-of-oxford/2008/r/2/iii/solution

Opposite vertices differ in all three bits. Thus the four added edges are

000 -! 111, 001 -! 110, 010 -! 101, 011 -! 100.

They form a perfect matching and raise the degree of every vertex by one.

 New to topics? Read the docs here!