MATH 2106 Foundations of Math Proof Homework 5


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MATH 2601 - FoMP - Homework 5 

Problem 1. Suppose that G is a planar graph on n vertices and m ≥ 2 edges, but with no 3-cycles. Then show that m ≤ 2n − 4.

Hint: As in the proof done in class, use the Euler characteristic that n−m+f = 2, for a connected planar graph drawn in the plane with f = #faces, and n and m being as above. 

Problem 2. Show that K5 and K3,3 are nonplanar, using the upper bounds on the number of edges in a planar graph. 

Additionally, the following problems from Hammack’s book: Chapter 8: 2, 8, 18 Section 11.1: 8, 16 Section 11.2: 4, 6, 10

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