# What is the weight wt of your minimum spanning tree t

This preview shows pages 3–4. Sign up to view the full content.

right. What is the weight w(T) of your minimum spanning tree T? There are several different correct solutions. First, in some order you will take two of the three edges from the "1" 3- cycle: de, ef, fd. Then you will need both "2" edges in some order: ae and ac. Then exactly one of the two "3" edges: ab or bd. For any of the 6 possible trees T, w(T) = 9. _________________________________________________________________ 6. (15 pts.) (a) Suppose G 1 and G 2 are nontrivial graphs. What does it mean mathematically to say that G 1 and G 2 are isomorphic?? [This is really a request for the definition!] Two graphs G 1 and G 2 are isomorphic if there is a bijection φ : V(G 1 ) V(G 2 ) such that uv ε E(G 1 ) if, and only if φ (u) φ (v) ε E(G 2 ). (b) Sketch two graphs G and H that have the degree sequence s: 2, 2, 2, 2, 2, 2 and have the same order and size, but are not isomorphic. Explain briefly how one can readily see that the graphs are not isomorphic. Since G is not connected and H is connected, G and H cannot be isomorphic. Why? Any graph isomorphic to H must be connected. (c) Explicitly realize C 5 and its complement below. [You may provide carefully labelled sketches.] Next, explicitly define an isomorphism from C 5 to its complement that reveals that C 5 is self-complementary. Define φ from C 5 to its complement by φ (a) = a, φ (b) = c, φ (c) = e, φ (d) = b, and φ (e) = d. φ is a bijection, and its easy to check uv is an edge in C 5 exactly when φ (u) φ (v) is an edge in the complement of C 5 . [There are only 5 edges to check.] How many isomorphisms are there??

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
TEST2/MAD3305 Page 4 of 4 _________________________________________________________________ 7. (10 pts.) Find a minimum spanning tree for the weighted graph below by using only Prim’s algorithm and starting with the vertex g. When you do this, list the edges in the order that you select them from left to right. What is the weight w(T) of your minimum spanning tree T? Beginning with vertex g, you should obtain edges in the following order: ge, ef, fb, ba, ed, dc. There is only one spanning tree, and its weight is w(T) = 31. You can check the edges, but not their order using Kruskal’s algorithm.
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern