Hamming graph
Cartesian product of complete graphs From Wikipedia, the free encyclopedia
Hamming graphs are a special class of graphs named after Richard Hamming and used in several branches of mathematics (graph theory) and computer science. Let S be a set of q elements and d a positive integer. The Hamming graph H(d,q) has vertex set Sd, the set of ordered d-tuples of elements of S, or sequences of length d from S. Two vertices are adjacent if they differ in precisely one coordinate; that is, if their Hamming distance is one. The Hamming graph H(d,q) is, equivalently, the Cartesian product of d complete graphs Kq.[1]
Hamming graph | |
---|---|
Named after | Richard Hamming |
Vertices | qd |
Edges | |
Diameter | d |
Spectrum | |
Properties | d(q – 1)-regular Vertex-transitive Distance-regular[1] Distance-balanced[2] |
Notation | H(d,q) |
Table of graphs and parameters |

In some cases, Hamming graphs may be considered more generally as the Cartesian products of complete graphs that may be of varying sizes.[3] Unlike the Hamming graphs H(d,q), the graphs in this more general class are not necessarily distance-regular, but they continue to be regular and vertex-transitive.
Special cases
- H(2,3), which is the generalized quadrangle G Q (2,1)[4]
- H(1,q), which is the complete graph Kq[5]
- H(2,q), which is the lattice graph Lq,q and also the rook's graph[6]
- H(d,1), which is the singleton graph K1
- H(d,2), which is the hypercube graph Qd.[1] Hamiltonian paths in these graphs form Gray codes.
- Because Cartesian products of graphs preserve the property of being a unit distance graph,[7] the Hamming graphs H(d,2) and H(d,3) are all unit distance graphs.
Applications
The Hamming graphs are interesting in connection with error-correcting codes[8] and association schemes,[9] to name two areas. They have also been considered as a communications network topology in distributed computing.[5]
Computational complexity
It is possible in linear time to test whether a graph is a Hamming graph, and in the case that it is, find a labeling of it with tuples that realizes it as a Hamming graph.[3]
References
External links
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