Definition 4.2 Let G be a nontrivial connected graph. A cycle Ct in G
is said to be minimal (minimal cycle or mt-cycle) if Ct does not contain any
cycle of order less than t. The mt-cycle derivative of G, denoted by mtG 0
is the graph obtain from G by taking the mt-cycles of G as vertices in mtG 0
and two vertices in mtG 0 are adjacent if and only if the two mt-cycles in G
corresponding to these vertices have an edge in common.