# A counterexample to a conjecture of Jafari Rad and Volkmann

Document Type : Short notes

Authors

Department of Mathematics, University of Blida 1. B.P. 270, Blida, Algeria

Abstract

In this short note, we disprove the conjecture of Jafari Rad and Volkmann
that every $\gamma$-vertex critical graph is $\gamma _{R}$-vertex critical,
where $\gamma (G)$ and $\gamma _{R}(G)$ stand for the domination number and
the Roman domination number of a graph $G$, respectively.

Keywords

Main Subjects

#### References

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409.
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