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Matrix multiplication exponent equals 2

Determine whether the matrix multiplication exponent ω—defined as the smallest real number for which multiplying two n×n matrices can be done in O(n^{ω+ε}) time for all ε>0—equals 2.

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Background

The paper reviews the long-standing effort to reduce the exponent ω of square matrix multiplication, currently bounded above by 2.371339 via the authors’ method. A trivial lower bound ω ≥ 2 follows from output size, and despite decades of work no larger lower bound is known. This context has led to the prevailing belief in the field that ω might be exactly 2.

The authors explicitly note this widely held conjecture while discussing known limitations of existing approaches, motivating further methodological innovations such as their more asymmetric laser-method analysis.

References

No larger lower bound is known, leading many to optimistically conjecture that ω=2.

More Asymmetry Yields Faster Matrix Multiplication (2404.16349 - Alman et al., 25 Apr 2024) in Section 1 (Introduction)