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Q3.a) Show that every planar graph has at least one vertex whose degree is s 5. Use a proof by contradiction b) Using the above fact, give an induction proof that every planar graph can be colored...
(2) Recall the following fact: In any planar graph, there exists a vertex whose degree is s 5 Use this fact to prove the six-color theorem: for any planar graph there exists a coloring with six colors, i.e. an assignment of six given colors (e.g. red, orange, yellow, green, blue, purple) to the vertices such that any two vertices connected by an edge have different colors. (Hint: use induction, and in the inductive step remove some verter and all edges...
Can some one please help me with this two questions. Thank you! fact that every planar graph has a vertex of degree s 5 to give a simple induction proof that every planar graph can be 6-colored. What can be said about the chromatic number of a graph that has Kn as a subgraph? Justify your answer
5. Let G is a simple planar graph containing no triangles. (i) Using Euler's formula, show that G contains a vertex of degree at most 3. (ii) Use induction to deduce that G is 4-colorable-(v). 5. Let G is a simple planar graph containing no triangles. (i) Using Euler's formula, show that G contains a vertex of degree at most 3. (ii) Use induction to deduce that G is 4-colorable-(v).
COMP Discrete Structures: Please answer completely and clearly. (3). (5). x) (4 points) If k is a positive integer, a k-coloring of a graph G is an assignment of one of k possible colors to each of the vertices/edges of G so that adjacent vertices/edges have different colors. Draw pictures of each of the following (a) A 4-coloring of the edges of the Petersen graph. (b) A 3-coloring of the vertices of the Petersen graph. (e) A 2-coloring (d) A...