The K-coloring of an undirected graph G = (V, E) is a function C: V ➝ {0, 1, ......, K-1} such that c(u) ≠ c(v) for every edge (u, v) ∈ E Which of the following is not correct?

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UGC NET Computer Science (Paper 2) Dec 2018 Paper
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  1. G has no cycles of odd length
  2. G has cycle of odd length
  3. G is 2-colorable
  4. G is bipartite

Answer (Detailed Solution Below)

Option 2 : G has cycle of odd length
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UGC NET Paper 1: Held on 21st August 2024 Shift 1
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A k- coloring of a graph G is mapping f: V(G) -> {set of k elements called colors}, such that adjacent vertices are mapped onto different elements.

A graph is called k – colourable, if it has a k-coloring. A k-coloring of a graph G(V, E) is a partitioning V = V1 U V2 U V………… U Vk into at most k independent sets of G.

Properties of K- colourable graph are:

1) A cycle of length n>=3 is – chromatic if n is even and 3- chromatic if n is odd

2) A graph is bi- colourable (2- chromatic) if and only if it has no odd cycles.

3) A non - empty graph G is bi colourable if and only if G is bipartite.
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