A simple unlabeled graph whose connectivity is considered purely on the basis of topological equivalence, so that two edges 
and 
joined by a node 
of degree two are considered equivalent to the single edge
.
Topological Graph
See also
Match ProblemExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Topological Graph." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/TopologicalGraph.html