Degrees of Vertices I: Is it Possible?

  • Context: MHB 
  • Thread starter Thread starter Joystar77
  • Start date Start date
  • Tags Tags
    Degrees
Click For Summary
SUMMARY

In the discussion titled "Degrees of Vertices I: Is it Possible?", it is established that a graph with vertex set V = {v1, v2, v3, v4, v5} cannot have vertex degrees of 3, 6, 2, 1, and 5. The calculation shows that the sum of the degrees equals 17, leading to a total edge count of E = 8.5, which is not feasible since the number of edges must be a whole number. Therefore, it is definitively concluded that such a graph configuration is impossible.

PREREQUISITES
  • Understanding of graph theory concepts, specifically vertex degrees
  • Familiarity with the Handshaking Lemma in graph theory
  • Basic knowledge of mathematical operations involving integers and decimals
  • Ability to analyze and interpret graph structures
NEXT STEPS
  • Study the Handshaking Lemma in detail to understand vertex degree relationships
  • Explore examples of valid and invalid graph configurations based on vertex degrees
  • Learn about Eulerian and Hamiltonian graphs and their properties
  • Investigate the implications of fractional edges in theoretical graph scenarios
USEFUL FOR

This discussion is beneficial for students and professionals in mathematics, computer science, and graph theory, particularly those interested in the properties and limitations of graph structures.

Joystar77
Messages
122
Reaction score
0
Let G be a graph with vertex set V = {v1, v2, v3, v4, v5}.

Is it possible for the degrees of the vertices to be 3, 6, 2, 1, 5, respectively? Why or why not?

2E = deg v1 + deg v2 + deg v3 + deg v4 + deg v5

2E = 3 + 6 + 2 + 1 + 5

2E = 17

E = 8.5

Is this correct to say that yes it is possible for the degrees of the vertices to be 3, 6, 2, 1, 5 because you end up with the number of edges being a decimal number?

Is it correct to say no that its not possible for the degrees of the vertices to be 3, 6, 2, 1, 5 because you end up with the number of edges being a decimal number?
 
Physics news on Phys.org
Joystar1977 said:
Let G be a graph with vertex set V = {v1, v2, v3, v4, v5}.

Is it possible for the degrees of the vertices to be 3, 6, 2, 1, 5, respectively? Why or why not?

2E = deg v1 + deg v2 + deg v3 + deg v4 + deg v5

2E = 3 + 6 + 2 + 1 + 5

2E = 17

E = 8.5

Is this correct to say that yes it is possible for the degrees of the vertices to be 3, 6, 2, 1, 5 because you end up with the number of edges being a decimal number?

Is it correct to say no that its not possible for the degrees of the vertices to be 3, 6, 2, 1, 5 because you end up with the number of edges being a decimal number?
The number of edges in a graph cannot be other than a whole number. Thus there is no graph possible which has vertices of degrees 3, 6, 2, 1, 5.
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
Replies
3
Views
2K
  • · Replies 19 ·
Replies
19
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 8 ·
Replies
8
Views
2K
Replies
3
Views
3K
  • · Replies 5 ·
Replies
5
Views
1K