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Matrix Multiplication Exponent


The matrix multiplication exponent omega_F over a field F is the infimum of the exponents tau such that, for every epsilon>0, two n×n matrices over F can be multiplied with O(n^(tau+epsilon)) arithmetic operations. The constant in the big-O notation may depend on epsilon but not on n. The operations counted are addition, subtraction, and multiplication of elements of the field; their bit complexity is a different question.

The usual matrix multiplication algorithm uses O(n^3) operations. Recursive use of Strassen's formulas gives

 omega_F<=(ln7)/(ln2)=2.807354922....

The lower limit 2 comes from the n^2 entries of a general product, and the conjecture that omega_F=2 remains open. The exponent describes asymptotic growth and does not by itself determine which algorithm is fastest at a given finite size (Strassen 1969).

OpenAI (2026a) announced

 omega_C<=9/4.

Equivalently, the claim gives O(n^(9/4+epsilon)) arithmetic operations for every epsilon>0 over the complex numbers. It does not claim this bound over every field, a practical crossover size, or an improvement in bit complexity. The release attributes the argument to an unreleased internal OpenAI model and supplies a Lean formalization of the bound. As of Oct. 7, 2026, VibeMathed (2026) had read the formal statement but had not independently rebuilt it, and independent specialist verification of the complete proof had not been reported.

A separate announcement by OpenAI (2026c) gives omega_F<2.371054886006746 over every fixed field F, including every positive characteristic. This bound has broader field scope than the sharper complex-number bound above. Both statements count arithmetic operations. The release proofs have not been independently verified here.

OpenAI (2026b) separately announced omega<2.258 over every field of characteristic zero and over all positive characteristics outside one finite exceptional set. In characteristic zero, the same manuscript claims that multiplying an n×n^(0.465) matrix by an n^(0.465)×n matrix requires n^(2+o(1)) arithmetic operations, and that the corresponding exponent for n×n^(0.709) by n^(0.709)×n multiplication is less than 2.092. The latter rectangular bound also has the finite-exception transfer to positive characteristic; the 0.465 claim does not assert that transfer.


See also

Bit Complexity, Matrix Multiplication, Multiplicative Complexity, Strassen Formulas

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References

OpenAI. "An Upper Bound of 9/4 for the Matrix Multiplication Exponent." Oct. 2, 2026a. https://github.com/openai/math/blob/adc7f1241b42e322a6451854ab7e4b4c146bf78a/preprints/Matrix-Multiplication-Nine-Fourths-October-2-2026/paper.pdf.OpenAI. "Complex Matrix Multiplication Below 2.258 and Rectangular Bounds." Sep. 24, 2026b. https://github.com/openai/math/blob/adc7f1241b42e322a6451854ab7e4b4c146bf78a/preprints/Complex-Matrix-Multiplication-Below-2.258-and-Rectangular-Bounds-September-24-2026/Complex-Matrix-Multiplication-Below-2.258-and-Rectangular-Bounds-September-24-2026.pdf.OpenAI. "Staggered Extraction for Exact Matrix Multiplication Over Every Field." Sep. 24, 2026c. https://github.com/openai/math/blob/adc7f1241b42e322a6451854ab7e4b4c146bf78a/preprints/Staggered-extraction-for-exact-matrix-multiplication-over-every-field-September-24-2026/Staggered-extraction-for-exact-matrix-multiplication-over-every-field-September-24-2026.pdf.Strassen, V. "Gaussian Elimination Is Not Optimal." Numer. Math. 13, 354-356, 1969. https://doi.org/10.1007/BF02165411.VibeMathed. "Matrix Multiplication Exponent at Most 9/4 over the Complex Numbers." Oct. 7, 2026. https://vibemathed.com/problem/matrix-multiplication-exponent-9-4.

Cite this as:

Weisstein, Eric W. "Matrix Multiplication Exponent." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/MatrixMultiplicationExponent.html

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