A graphH with nodes is an extension of a graph G with nnodes if each maximal subgraph of H contains G. Trivial extension of a graph G is the connection of graph G and the singleton graph (i.e. we add one node to the graph G and this node join with each node of G). T-irreducible extension of graph G is an extension of the graph G which is obtained by removing maximal set of edges from the trivial extension of G. One of T-irreducible extensions is constructed for an arbitrary union of cycles and paths.
