
How Did We Get Here? Permutations as Genome Rearrangements. 371
9.3.1.1 Variations of the Cycle Graph
The concept of cycle graphs is a very important one, and as such, it has
been introduced several times, in slightly different (but essentially equivalent)
versions. One such version identifies vertices p
0
=0andp
n+1
= n +1 so
that these two vertices become one, and leaves all the other rules unchanged,
except that i +1andi − 1 are now meant modulo n. So the new vertex (let
us call it 0), now has four edges adjacent to it, namely one edge of each color
leaving it, and one edge of each color arriving at it, just like any other vertex.
This “circular” version ...