Small but concrete improvement to the matrix multiplication exponent using ML-backed optimization
Researchers report a new, slightly better upper bound on the matrix multiplication exponent ω: they show ω < 2.371177, improving the previous best ω < 2.371339. The exponent ω determines how the cost of multiplying two n×n matrices grows with n. If ω is smaller, large matrix products can in principle be done with fewer arithmetic steps. Finding better upper bounds on ω is a long‑running theoretical problem in computer science.
The paper focuses on a computer‑assisted part of the current best methods, a refinement of the “laser method” known as combination loss analysis. That method reduces the mathematical question to a hard non‑convex optimization problem. The authors reformulated that optimization problem so it can be solved in a larger, more detailed setting than before. Concretely, one tuning parameter of the method is the maximum recursion level ℓ*; previous work used ℓ* = 3 with about 25,000 optimizable numbers. By switching to a gradient‑based solver implemented in Jax, and using hardware parallelization, the authors were able to handle ℓ* = 4, raising the number of parameters to about 7 million.
They then combined modern optimization techniques with an automated refinement called AlphaEvolve. The paper says the gradient‑based approach alone produced an improvement of about 0.97×10^−4 in the bound on ω. Using AlphaEvolve to further refine the solution increased that improvement to about 1.62×10^−4, giving the reported bound ω < 2.371177. The underlying mathematical object being decomposed is related to the Coppersmith–Winograd tensor, and any feasible solution to the optimization produces a valid upper bound on ω.
Why this matters: matrix multiplication underpins many areas of computing, from scientific simulation to machine learning. Progress on ω advances our theoretical understanding of those basic costs. This work is also notable for bringing modern machine‑learning optimization tools into a proof‑adjacent role, showing that gradient methods and automated search can push a delicate, high‑dimensional mathematical optimization forward.