Drexel dragonThe Math ForumDonate to the Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » Math Topics » discretemath

Topic: The handshake lemma question?
Replies: 3   Last Post: Feb 12, 2012 1:56 PM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
joe

Posts: 3
Registered: 2/12/12
The handshake lemma question?
Posted: Feb 12, 2012 12:15 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

Hi, everyone I'm having a bit of trouble with this problem. I don't understand it at all. Any help will be appreciated

Consider a planar graph with v vertices, e edges, and f face.

A)The degree of a vertex is de?ned as the number of edges touching it. Let?s
de?ne in an analogous way the degree of a face to be the number of edges encountered when we complete a walk around its boundary. What happens if we
add up the degrees of all faces (note: this includes the outer face too).

B)From part (a), conclude a relation between the sum of degrees of vertices
and the sum of degrees of faces.



Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2014. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.