Exercise 13.

Find all spanning trees of the graph below. How many different spanning trees are there? How many different spanning trees are there up to isomorphism (that is, if you grouped all the spanning trees by which are isomorphic, how many groups would you have)?

A graph with six vertices labeled a through f. Vertices a, b, and c form a triangle (with their edges), with a directly above b and c to the right of both. Vertex c is then adjacent to vertices d, f, and e, with d directly above f and e farther to the right. Vertices d and f are also adjacent to e.
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