Matrix multiplication exponent equals 2
Determine whether the exponent ω of square matrix multiplication over the reals is equal to 2.
References
Were the exponent of matrix multiplication ultimately shown to be 2 (as is conjectured, although progress in reducing it has slowed considerably), the complexity of the algorithms in would become \tilde{O}(n{2+1/6}) while for the algorithm of it would become O(n{2+1/18}).
No larger lower bound is known, leading many to optimistically conjecture that ω=2.
We further show that the above algorithm for $t = 2$ can be implemented in time $n{\omega + o(1)}$ for $\omega$ the constant of square matrix multiplication and succeeds when $\lambda > 0.3320$; under the folklore conjecture that $\omega = 2$, this runs in the nearly-linear time of the algorithm of Deshpande--Montanari while finding smaller cliques.
More precisely, the asymptotic rank of the $n\times n$ matrix multiplication tensor is $n\omega$ for some (unknown) constant $\omega$, the exponent of matrix multiplication.