universal fixer; domination
Given two disjoint copies of a graph $G$, denoted $G^1$ and $G^2$, and a permutation $\pi $ of $V(G)$, the graph $\pi G$ is constructed by joining $u \in V(G^1)$ to $\pi (u) \in V(G^2)$ for all $u \in V(G^1)$. $G$ is said to be a universal fixer if the domination number of $\pi G$ is equal to the domination number of $G$ for all $\pi $ of $V(G)$. In 1999 it was conjectured that the only universal fixers are the edgeless graphs. Since then, a few partial results have been shown. In this paper, we prove the conjecture completely.
 Gu, W.: Communication with S. T. Hedetniemi. Southeastern Conference on Combinatorics, Graph Theory, and Computing. Newfoundland, Canada, 1999.
 Gu, W., Wash, K.: Bounds on the domination number of permutation graphs
. J. Interconnection Networks 10 (2009), 205-217. DOI 10.1142/S0219265909002522
 Mynhardt, C. M., Xu, Z.: Domination in prisms of graphs: universal fixers
. Util. Math. 78 (2009), 185-201. MR 2499846
| Zbl 1284.05199