We now given an example of Corollary 2.5. In Figure 2, two original graphs,
the clones of two original graphs, and the glued graph are all Eulerian. The bold
graph in each of them illustrates the subgraph itself and an isomorphism f from
subgraph of G1 to one of G2 defined by f(ui) = vi for every i ∈ {1, 2, 3}.
Another special case arises when one of the original graphs is Eulerian and
another one is not. This case is stated in the following corollary.
Corollary 2.6. The glued graph of two connected graphs, one of these is Eulerian
and one is not, is Eulerian if and only if the following conditions hold:
1.) the clone of the non-Eulerian graph contains all odd vertices,
2.) every even vertex in clones of two original graphs is obtained from both
even vertices in two original graphs.