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arXiv · 1912.10199

Clique number and Chromatic number of a graph associated to a Commutative Ring with Unity

T. Kavaskar
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Abstract

Let R be a commutative ring with unity (not necessarily finite). The ring R consider as a simple graph whose vertices are the elements of R with two distinct vertices x and y are adjacent if xy=0 in R, where 0 is the zero element of R. In 1988 [8], Beck raised the conjecture that the chromatic number and clique number are same in a graph associated to any commutative ring with unity. In 1993 [2], Anderson and Naseer disproved the conjecture by giving a counter example of the conjecture (Note that, till date this is a only one counter example). In this paper, we find the clique number and bounds for chromatic number of a graph associated to any finite product of commutative rings with unity in terms of its factors (In particular, if R is finite which is not a local ring, we obtain the clique number and bounds for chromatic number of a graph associated to R in terms of its local rings). As a consequence of our results, we construct infinitely many counter examples of the above conjecture. Also, some of the main results, proved by Beck in 1988 [8] and Anderson and Naseer in 1993 [2] are consequences of our results.

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T. Kavaskar. 2020-01-07. Clique number and Chromatic number of a graph associated to a Commutative Ring with Unity. https://arxiv.org/abs/1912.10199

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