If there exists a sequence F = H0; H1;:::;H‘ = H (‘¿0) of
edge-induced subgraphs of size k in G such that Hi+1 is obtained from Hi by an
edge rotation for i = 0; 1;:::;‘ − 1, then we say that F is r-transformed into H. The
minimum number of edge rotations required to r-transform F into H is called the
rotation distance dr(F; H).