In book "Algorithms, 4th Edition by Robert Sedgewick and Kevin Wayne" is written
The Kendall tau distance between two rankings is the number of pairs that are in different order in the two rankings. For example, the Kendall tau distance between 0 3 1 6 2 5 4 and 1 0 3 6 4 2 5 is four because the pairs 0-1, 3-1, 2-4, 5-4 are in different relative order in the two rankings, but all other pairs are in the same relative order.
But what about 6-0, 6-3 and etc, these pairs are in different relative order too. I don't understand this explanation. May anybody explain it well, please?