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Graph Tensor


A graph tensor of positive integer bond dimension b over C is the tensor associated with a finite graph by placing sum_(i=1)^(b)e_i tensor e_i on each graph edge and grouping all tensor factors incident to the same graph vertex into a single factor. Here e_1,...,e_b is the standard basis of C^b (Christandl et al. 2019). This construction is distinct from the graph tensor product.

The asymptotic tensor rank of a tensor T is

 R^~(T)=lim_(k->infty)R(T^( tensor k))^(1/k),

where R is tensor rank and corresponding vertex factors are grouped together in each tensor power. For the bond-dimension-2 tensor T(K_n) of the complete graph with n>=2, Zhou (2026) proved

 |_n^2/4_|<=log_2R^~(T(K_n))<=n^2/4.

Here |_x_| is the floor function. In particular, equality holds for even n. Zhou (2026) attributes the central construction to an AI-generated argument developed under human mathematical direction.


See also

Tensor, Tensor Rank

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References

Christandl, M.; Vrana, P.; and Zuiddam, J. "Asymptotic Tensor Rank of Graph Tensors: Beyond Matrix Multiplication." Comput. Complexity 28, 57-111, 2019. https://doi.org/10.1007/s00037-018-0172-8.Zhou, H. "Asymptotic Rank of Complete Graph Tensors." 25 Oct 2026. https://arxiv.org/abs/2610.34273.

Cite this as:

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

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