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Commuting Graph


The commuting graph of a noncommutative ring R is the simple graph whose vertices are the elements outside the ring center, with two distinct vertices adjacent iff the elements commute, xy=yx (Akbari et al. 2004). For a matrix ring, adjacency is the relation of being commuting matrices.

Shahverdi and Shahverdi (2026) proved that if a ring R with multiplicative identity has a commuting graph isomorphic to that of M_(2n)(F_q) for any n>=1 and any finite field F_q, then R is isomorphic to that matrix ring. Thus the commuting graph determines these finite matrix rings of even size. Shahverdi and Shahverdi (2026) report AI assistance with checking the proof.


See also

Commuting Matrices, Matrix Ring, Ring Center

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References

Akbari, S.; Ghandehari, M.; Hadian, M.; and Mohammadian, A. "On Commuting Graphs of Semisimple Rings." Lin. Alg. Appl. 390, 345-355, 2004. https://doi.org/10.1016/j.laa.2004.05.001.Shahverdi, H. and Shahverdi, V. "Finite Matrix Rings of Even Size Are Determined by Their Commuting Graphs." 27 Oct 2026. https://arxiv.org/abs/2610.37150.

Cite this as:

Weisstein, Eric W. "Commuting Graph." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/CommutingGraph.html

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